Subject: [HELP] Water Leakage at Home – Can’t Find the Source - Page 1
Forum section: electronics / beginners

author: Eassssse
author_rank: Newbie
timestamp: August 04, 2025, 05:49:05 am
content: Hi everyone,I know this forum is more about electronics, but I’ve seen a lot of practical and knowledgeable people here, so I hope it’s okay to ask for some off-topic help.I’ve recently discovered a water leak somewhere in my home’s plumbing system, but I can’t figure out exactly where it’s coming from. There’s no obvious dripping or visible damage, but I can hear a faint sound of water flow even when all faucets are turned off. My water meter is also slowly spinning, which confirms there’s a leak.Here’s what I’ve tried so far:Turned off all water-using appliances and fixtures inside the house.Checked under sinks, behind toilets, and around the water heater.Walked around the house to listen for leaking sounds.Monitored the water meter for signs of usage.Unfortunately, nothing obvious is showing up, and I’m not sure whether the leak is under the floor, in the walls, or even outside underground.Does anyone here have experience with this kind of issue or suggestions on how to locate a hidden leak? Any tips, tools, or diagnostic methods would be appreciated. I’m trying to avoid calling a plumber immediately if I can narrow it down a bit myself first.Thanks in advance!Best regards,Eassssse

author: Berni
author_rank: Super Contributor
timestamp: August 04, 2025, 06:00:06 am
content: This is why having shutoff valves for each section of a house is useful, it can isolate the fault to a smaller area of the house. (both for locating and letting you keep the water on for the rest of the house while the fault is being fixed)Otherwise thermal cameras can be good at seeing leaks because damp areas get evaporation cooling so they get colder than ambient. Generally if you have a leak anywhere in a masonry wall the wall will soak it up and become moist all over. If you got drywall then it might be tricky because the leaking water could be sticking to the outside of a pipe and running a fair distance away from the actual leak. However seeing that you didn't visually notice anything damp after such a long time id say there is a high chance the leaking pipe is somewhere down near the foundations and the leaking water is just draining down into the earth below.I suppose one thing you could try as a last resort is draining your plumbing and hooking up an air compressor set for ~2 bar to one of the taps (Do NOT send 10 bar into that) to turn your water leak into an air leak. Air leaks are louder and so you might be able to trace a hissing sound somewhere.

author: Sorama
author_rank: Frequent Contributor
timestamp: August 04, 2025, 06:12:13 am
content: Quote from: Eassssse on August 04, 2025, 05:49:05 amOur building physics department does this sort of leak detection 5 times a day.They use either an acoustic measuring device in combination with a compressor to locate the leak, or inject tracer gas (which is 95% N2 with 5% H2). Then, with a sniffer, you walk over the floor or where you think the piping is (for which we have tracing devices too).What kind of piping do you have?Do have have visual damage somewhere ?Have you checked whether the safety valve under the electrical heater (if you have one) is leaking?By using a manometer attached to a cold water pipe you can measure for any pressure drops, after you closed the main valve. If within 15 minutes the pressure (between 2 and 4 Bar) drops steadily, you know for sure you have a leak.They also use a lot IR camera to look for moisture in the floor or the walls.(That’s actually the first thing they do, in combination with measuring moisture of the floor/walls of they see something suspicious)Do the same on a hot water pipe.

author: brucehoult
author_rank: Super Contributor
timestamp: August 04, 2025, 06:33:35 am
content: Must be the water.

author: Sorama
author_rank: Frequent Contributor
timestamp: August 04, 2025, 06:43:51 am
content: Quote from: Berni on August 04, 2025, 06:00:06 amThat is actually not true, as there is commonly a flashing membrane just above the floor (at plinth level) just to prevent that.So generally, walls are not impacted unless there where the membrane was cut because of vertical piping for radiators or electricity.That cut will make a shortcut and bypass the membrane.

author: MrAl
author_rank: Super Contributor
timestamp: August 04, 2025, 06:50:34 am
content: Quote from: Eassssse on August 04, 2025, 05:49:05 amHi,Do you have hot water heating in your house?Some, if not all, hot water systems have a direct connection to the cold water pipe in the home. That means if the hot water pipes for the heating has a leak, it will draw more water from the cold-water pipe. That would include radiator leaks where the cold water keeps flowing into the heating system.Obviously if you have electric heating this would not happen.

author: Poroit
author_rank: Frequent Contributor
timestamp: August 04, 2025, 06:51:39 am
content: G'day Eassssse,How old is the house and the plumbing?Ditto as per Sorama ..... piping type?Where is the water meter mounted in relation to the house?Eg in Oz many water meters are located near the property boundary, so there can be a 10 meter long pipe run to the house.Do you have a reticulation system for Gardens?

author: Sorama
author_rank: Frequent Contributor
timestamp: August 04, 2025, 06:58:58 am
content: Quote from: MrAl on August 04, 2025, 06:50:34 amNo, heating system with radiators is not possible as it is a CLOSED system.

author: BradC
author_rank: Super Contributor
timestamp: August 04, 2025, 07:00:40 am
content: I went through this about 10 years ago. Mine was in the hot water plumbing, verified by isolating the HWS.I ended up borrowing a medical stethoscope and following the pipe routes from the HWS until I could hear noise. In my case it appeared to be coming from under the bath, so I knocked out half a brick and poked a camera (car reversing camera & 21W tail light taped to a stick) in to have a look. It was actually coming from where the pipe passed under the wall from the adjacent toilet, so I had to pull up some concrete floor to expose the leak. Bastard of a job.Best of luck!

author: Berni
author_rank: Super Contributor
timestamp: August 04, 2025, 07:08:55 am
content: Quote from: Sorama on August 04, 2025, 06:43:51 amGuess that depends on the building codes in the part of the world.Here we typically only have a moisture membrane to separate the foundation wall from the earth outside so that it doesn't wick moisture from the ground. The walls that go above ground are simply brick directly on the concrete slab along with some rebar sticking out of the slab here and there to hold the two together. Then plumbing pipes are run directly in the brick wall and covered up with plaster. So if you have a joint start leaking or rust trough (iron pipes were popular back then) the water just leaks into the surrounding brick and wicks out into a big moist spot on the wall. Exception are hot water pipes as those tend to have a insulating sleeve over them, so water could follow the sleeve back out of a wall somewhere.

author: Sorama
author_rank: Frequent Contributor
timestamp: August 04, 2025, 07:21:19 am
content: Quote from: Berni on August 04, 2025, 07:08:55 amIn general there are 4 to 5 flash membranes ( inner and outer part of a cavity wall).It would be very strange if your country only puts one.There is always a horizontal membrane just above floor in the inner part of a cavity wall.It’s technically obligatory.

author: tggzzz
author_rank: Super Contributor
timestamp: August 04, 2025, 07:38:20 am
content: In old houses plumbing can be.... strange and unexpected.While a student the boiler in her house failed, so naturally all heating and hot water was lost. Except, that is in one of the bathrooms where the hot water continued to work normally.Clearly the house had been split into two houses sometime in the dim and distant past, but the plumbing hadn't been completely separated!Be aware that water can appear a long way from the leak, downhill, uphill, sideways.Check header tanks and toilet cisterns aren't overflowing.If you can access the drains via a manhole, see if there is water continually flowing away.

author: golden_labels
author_rank: Super Contributor
timestamp: August 04, 2025, 08:42:21 am
content: A black hole has formed inside your plumbing system. Call CERN.Here’s an idea. What about trying to record the pipes with a microphone and finding where the water flowing sound can no longer be heard? A microphone directly touching the wall should be able to pick up sound much better than your ear.That assumes you know where pipes at your home are located.

author: Berni
author_rank: Super Contributor
timestamp: August 04, 2025, 09:31:22 am
content: Quote from: Sorama on August 04, 2025, 07:21:19 amDepends on the area and the building methods. Usually extensive use of barrier foils is used more for framed construction.In my part of the world we have pretty deep water tables,so we likely don't need to worry about moisture nearly as much. Layer of bitumen around the foundation walls is all we have and it results in a dry basement. Very old houses don't have it and those have a problem that rain gets wicked from the earth up the walls. Our roofs typically also have a lot of overhang so that keeps most of the rain from touching the exterior walls. But internal walls never have any special moisture insulation, ceramic tiles take care of bathrooms well enough to not need any.If the area has a high water table the requirements are very different. Those in some cases need sump pumps to constantly remove water, otherwise the basement turns into a literal swimming pool.

author: themadhippy
author_rank: Super Contributor
timestamp: August 04, 2025, 09:37:31 am
content: got any storage tanks,including toilet cisterns? check the fill valve is shutting off

author: Sorama
author_rank: Frequent Contributor
timestamp: August 04, 2025, 10:43:16 am
content: Quote from: Berni on August 04, 2025, 09:31:22 am??If you think membranes have anything to do with water tables then really, you don’t know a single thing of how buildings are constructed.Unless in “your part of the world” (as if it doesn’t rain nor there is moist in the soil)Your buildings are built exactly the same as in the rest of Europe.Also, membranes are a necessity for brick as well framed constructions.

author: Psi
author_rank: Super Contributor
timestamp: August 04, 2025, 10:57:03 am
content: Sounds can sometimes be hard for a human to fully isolate the exact direction.A very directional microphone and a oscilloscope can sometimes help you figure out the general location.You can compare direction and voltage from many locations around the house.Assuming you can get the house quiet enough that the drip shows up well on the scope.

author: Sorama
author_rank: Frequent Contributor
timestamp: August 04, 2025, 11:05:47 am
content: Quote from: Psi on August 04, 2025, 10:57:03 amAcoustic leak detection is never done with directional microphones, but with heavy floor touching vibration sensors.

author: Psi
author_rank: Super Contributor
timestamp: August 04, 2025, 11:26:14 am
content: Quote from: Sorama on August 04, 2025, 11:05:47 amtrue, but op is far more likely to have a directional microphone than a heavy floor mount vibration sensor.

author: voltsandjolts
author_rank: Unknown
timestamp: August 04, 2025, 11:35:15 am
content: Don't use a microphone, use a teenager. They hear a pin drop at 100yds.

author: Psi
author_rank: Super Contributor
timestamp: August 04, 2025, 12:09:27 pm
content: Also, be sure to rotate your head 90Deg when trying to figure out the height of the sound.Its far easier for a human to figure out left vs right than up vs down. Left vs right is simple amplitude. Up vs Down is based on reflections inside the ear.

author: Sorama
author_rank: Frequent Contributor
timestamp: August 04, 2025, 12:32:17 pm
content: Quote from: Psi on August 04, 2025, 11:26:14 am

author: Psi
author_rank: Super Contributor
timestamp: August 04, 2025, 12:47:42 pm
content: All I said was a directional microphone with a scope is better than your ears since you can record some data points and it's repeatable. It doesnt have to be the best solution to be better than trying to listen for where the sound is coming from and then trying to decide if it was louder or quieter than when you heard it before.A stethoscope can also be useful

author: wilfred
author_rank: Super Contributor
timestamp: August 04, 2025, 01:05:41 pm
content: I had a leak detection company check my place and they used compressed nitrogen to inject into the pipes (drained of water). Then they used a microphone to listen for the leak. The leak was in a pipe embedded within concrete slab. They were able to pinpoint it to within 20cm. It was a lot cheaper than having plumbers search it out. The slab was wet but the plumbers would have had 2-3 meters to dig within hence a leak detector reduce the amount of concrete that had to be removed to expose the pipe near the leak.Other times I have looked for the water. It has to be somewhere. If it is above ground I would go around the entire outer perimeter walls looking firstly for drips but if the wall and or foundations are brick then the mortar will usually show water by darkening with respect to dry mortar above the level of the leak or distant from it.If you can hear the leak it has to have a reasonable flow that must show up somewhere. A slow drip will likely be silent apart from the actual dripping. Only water under pressure will make a sound as if it is spraying out of a small fracture. Water always leaks from the point of least resistance if you slightly open taps can you tell if the sound continues above the sound of the flow out of the taps?If the leak is underground then the ground will eventually become wet and soft underfoot.Can you turn off the water to the property to absolutely isolate the plumbing from water pressure? If you do and you still hear sound than you don't have a leak. Does the water meter indicate the flow rate at a level you can measure in litres/hour to give you an idea of just what the flow is and what sort of wet area you should expect to find?With hot water pipes after the water heater they can feel warm to the touch if water is flowing. Otherwise they will reflect the time since you last used hot water and will eventually cool to the same as the cold water pipes. You shouldn't need fancy devices to detect a pipe that has flowing hot water. Even a slight leak will take the chill off the pipe when compared to a cold water pipe. Do this early in the morning before anyone in the household has used hot water and the pipes have had the maximum time overnight to cool after showers and dishwashing.Until you actually find water where it ought not be, you can still be mistaken.

author: Sorama
author_rank: Frequent Contributor
timestamp: August 04, 2025, 01:48:48 pm
content: Quote from: Psi on August 04, 2025, 12:47:42 pmYou CANNOT hear a leak in an underground pipe.That’s nonsense.

author: Sorama
author_rank: Frequent Contributor
timestamp: August 04, 2025, 01:54:22 pm
content: Quote from: wilfred on August 04, 2025, 01:05:41 pmAs explained, the gas used is not 100% nitrogen, but a mixture of 95% nitrogen and 5% hydrogen.As hydrogen is the lightest molecule, it finds its way straight up and goes through light concrete.Then a sniffer is used to detect the hydrogen.You can also use this gas when practicing acoustic detection, but that is a though waste of money, as you can do the same with an air compressor.However, the combination of water and air (from the compressor) gives a rather easy to distinguish sound when going through a hole in a pipe.But it takes years of experience to hear the difference.

author: BILLPOD
author_rank: Frequent Contributor
timestamp: August 04, 2025, 02:07:02 pm
content: Good Morning Eassssse, First of all, welcome to the Forum. I'm curious what would lead you to an electronics forum to seek advice for a plumbing problem?If you wanted to find logical thinking minds, you did make a good choice, as you have, what I consider, some of the most logical, educated, and helpful minds of any forum on the internet. A lot of good ideas have been given to you, but I believe you need to provide more information, in order to help narrow the problem, like the type of construction you have, and where the water supply pipe enters the building, and if the meter is remote from the building. I especially like the idea of draining the entire system and filling it with compressed air. I'm not a plumbing expert, but being a homeowner for over 50 years, and a DIYer, I've experienced quite a few plumbing problems, but the one that most closely resembles yours was a similar minute leak that eventually led me to a toilet flush valve. Luckily, I had valves that would isolate various parts of my home. Also, shut off the water going into your hot water tank, which should prove or eliminate the hot water piping. Good luck, and be sure and post your eventual solution, and the method you used to track it down.

author: BradC
author_rank: Super Contributor
timestamp: August 04, 2025, 02:21:14 pm
content: Quote from: BILLPOD on August 04, 2025, 02:07:02 pmI went this route initially. Drained the whole system and pressurized it. After the compressor had run for a *considerable* time it occurred to me I was also pressurizing my 270L hot water storage tank which would have gone off like an explosive and probably taken out part of the house had something gone wrong. Our water pressure is usually about 6 bar and I had 8 bar of air in the system.Just be aware and don't do something potentially dumb like I did.

author: Kasper
author_rank: Frequent Contributor
timestamp: August 04, 2025, 03:35:08 pm
content: Quote from: BILLPOD on August 04, 2025, 02:07:02 pmThis is my guess as well.

author: golden_labels
author_rank: Super Contributor
timestamp: August 04, 2025, 06:57:03 pm
content: It would be great, if OP replied.

author: Seekonk
author_rank: Super Contributor
timestamp: August 04, 2025, 08:40:12 pm
content: sonic leak detector

author: MrAl
author_rank: Super Contributor
timestamp: August 05, 2025, 08:54:17 am
content: Quote from: Sorama on August 04, 2025, 06:58:58 amAre you sure about that?I ask because hot water systems can loose water through various means so they often have a connection to the mains water line. This is so new water can be added if there is a tiny leak or small loss somewhere. If there is a larger leak, this can lead to a lot of water usage.Here's a quote:"Hot water heating systems, whether they are gas or electric, typically receive their water from the municipal water supply or a well. This cold water enters the water heater and is then heated by a burner or heating element. "If yours really is closed then it is closed, but I wonder how you know that it is really completely closed.

author: Sorama
author_rank: Frequent Contributor
timestamp: August 05, 2025, 09:04:00 am
content: Quote from: MrAl on August 05, 2025, 08:54:17 amyou need to distinguish between hot water systems for consumption/washing and hot water for heating systems like radiators.Heating systems are of course a closed loop because water does not disappear in the heating system (apart from some very minor evaporation).Using (hot) water for consumption/washing is of course connected to the mains as the water that is used, is gone.

author: John Coloccia
author_rank: Super Contributor
timestamp: August 05, 2025, 09:17:48 am
content: Quote from: BILLPOD on August 04, 2025, 02:07:02 pmI'm surprised no one's suggested ripping out all the old-fashioned pipes, and just replace it with a micro.Personally, once I check my toilets, heating system, water treatment and do a general walk around, I'm calling someone. I might get lucky and find it on my own, but a pro that's got a lot of experience and the right tools will find it quickly.

author: SteveThackery
author_rank: Super Contributor
timestamp: August 05, 2025, 09:49:58 am
content: Here in the UK we mostly use 'combi' boilers. The cold mains water flows through a heat exchanger in the boiler on its way to the taps. Thus, the hot water to the taps is at mains pressure.The heating system is a closed loop and the water is directly heated in the boiler and pumped around the radiators. The boiler has a 'filling loop' which - when two valves are opened - connects the mains water to the closed heating circuit to add more water to it. The heating circuit has an expansion tank comprising a sealed vessel with a membrane down the middle. The heating circuit water is on one side of the membrane and air (or nitrogen) on the other. Water is added to the heating circuit via the filling loop until the pressure in the heating circuit reaches 1 to 1.5 bar, cold (typically).If the heating circuit has a leak the pressure gradually falls, as revealed by the pressure gauge on the boiler. If it falls below 0.5 bar (typically) the boiler will cut out.If the pressure in the heating circuit rises above 3 bar (typically) a pressure release valve opens and water is dumped into the condensate outlet pipe.The expansion vessel has a limited life. When the diaphragm fails, the air is expelled and the vessel fills with water. Thus it is no longer able to "buffer" the pressure rise when the water in the heating circuit is heated. As a result the pressure rises quickly and - when it reaches 3 bar - begins to be expelled through the pressure release valve. When the heating system switches off, the pressure falls quickly (due to the lack of buffering) and if enough water has been expelled, it will fall below 0.5 bar and the boiler locks out until more water is added to the heating circuit via the fill loop.Thus a frequent loss of pressure in the heating circuit does not always (not even usually) imply a leak. It is more likely due to a failed expansion vessel.

author: tggzzz
author_rank: Super Contributor
timestamp: August 05, 2025, 10:48:00 am
content: Quote from: SteveThackery on August 05, 2025, 09:49:58 amI've seen all that in my parent's heating system.What I don't understand and the heatingengineerstechnicians have never been able to explain is what the pressure meter is actually measuring.My parent's house was 4 stories (i.e. ~70ft) tall with the boiler in the basement. 1 bar is 32ft of water, so the height of the top-floor radiators should result in a pressure of at least 2 bars in the boiler radiator circuit. So what does a reading of 0.6bar (I've seen lower!) actually mean?It can't be the pressure relative to the mains pressure, since that was (1) much more than 2 bars and (2) was isolated (as you describe) by the manual valve inside the boiler.

author: Berni
author_rank: Super Contributor
timestamp: August 05, 2025, 11:57:33 am
content: The water in the central heating loops can get vacuum locked when you drain it.This sort of situation can make for a surprise when servicing the system, where you drain it and start taking it apart and seams like no water is flowing anymore. But then as you disturb it you get air bubbles traveling trough pipes and breaking the vacuum holding the water up, suddenly you have all the water in the radiators dumping down and out of the pipe you are taking apart, making a big mess. So it is a good idea to either shut both top and bottom valves on all the radiators so that it can't drain, or properly drain them by opening the little priming valves on the radiators to let air in.Here the pressure gauges on central heating show pressure relative to ambient (they show 0 bar when not connected) makes sense since that basically shows the height of the water column above the gauge + any extra pressure.Tho over pressure protection valves here are often not really routed to any drain, they just barf out onto the floor. Probably because that valve opening indicates something is wrong, so spilling on the floor gets the attention of the user that much more. Haven't really seen them open up, just sometimes leak slightly due to old age. (apart from firing up a wood furnace way too much and getting the water >120°C)

author: tggzzz
author_rank: Super Contributor
timestamp: August 05, 2025, 12:47:06 pm
content: Quote from: Berni on August 05, 2025, 11:57:33 amThati can understand!It is the 0 bar when there is a 15-20m head of water that baffles me.

author: m k
author_rank: Super Contributor
timestamp: August 05, 2025, 01:03:36 pm
content: Initial pressure?Bottom of expansion vessel to high point of circulation network in 10 meters is one limit.

author: BILLPOD
author_rank: Frequent Contributor
timestamp: August 05, 2025, 01:09:31 pm
content: Well, even if OP Eassssse, never comes back, I'm sure all of us picked up some plumbing knowledge; I know I did. Thanks to all who shared their knowledge and expertise.

author: tggzzz
author_rank: Super Contributor
timestamp: August 05, 2025, 01:10:09 pm
content: Quote from: m k on August 05, 2025, 01:03:36 pmI doubt it would "remember" the pressure 10 years ago!QuoteZero bar in boiler relative to what? Nothing in manual. Haven't found explanation on web. At least two installation technicians have never thought about it, and when I "encouraged" them to think about it they couldn't answer.

author: Berni
author_rank: Super Contributor
timestamp: August 05, 2025, 03:04:04 pm
content: Quote from: tggzzz on August 05, 2025, 12:47:06 pmYou can have pockets of vacuum in the system that are holding the water up. This is what causes the problem of draining the system by just opening the tap at the lowest point, some of the water will come out, but some gets held up above you by areas of vacuum because air doesn't have a way to get in. (But if you disturb that vacuum while working on the system you are gonna get wet as it suddenly dumps out)There can be multiple of these pockets in the system. Even if the total height of your pipework is 30m you could split it up into 3 sections of 10m that are held up by vacuum (especially since the pipework might be very twisty). Some of the separations possibly created by air that leaked in. Once this happens the whole system doesn't act like one big water column anymore. So the pressure gauge might only be seeing the water column in one section of pipework.Quote from: tggzzz on August 05, 2025, 01:10:09 pmSome of the pressure gauges we use for central heating have a feature of the front glass being able to rotate, that glass has an extra needle painted on it. The point is to set this needle at a pressure you wish to run at, then always top up the water in the system until the actual pressure matches that set pressure. When you look at it years later you can see exactly now far below the needle dropped. Some other central heating pressure gauges just have a extra red line painted at around 2.5 bar for you to fill the water to.Tho fair to say that these pressure gauges are pretty prone to sticking because they sit at the same pressure for very long periods. So if the pressure doesn't make sense, or doesn't go up as you fill it, it is worth giving the gauge a few procusive maintenance whacks to help unstick it.

author: m k
author_rank: Super Contributor
timestamp: August 05, 2025, 03:14:32 pm
content: Quote from: tggzzz on August 05, 2025, 01:10:09 pmNot boiler, the pump, cavitation prevention.So relative to internal pressure of sealed expansion vessel.

author: tggzzz
author_rank: Super Contributor
timestamp: August 05, 2025, 03:45:48 pm
content: Quote from: Berni on August 05, 2025, 03:04:04 pmSeems unlikely in my case.I bled the air out of the top floor radiators and the let water in until pressure had risen to 1.5bar. Then repeat a couple of times until no more gas was released. Thereafter radiators became hot, as expected.QuoteDefinitely a.simple gauge, needing grappling like an android barometer. Red plastic fiducial mark was moved by screwdriver blade, and then stayed where it was left.

author: Sorama
author_rank: Frequent Contributor
timestamp: August 05, 2025, 03:53:08 pm
content: probably a needle to set the maximum pressure...this is just an indicative needle...doesn't measure anything at all.

author: Terry Bites
author_rank: Super Contributor
timestamp: August 05, 2025, 04:15:12 pm
content: That looks like a really good and very cheap solution.

author: SteveThackery
author_rank: Super Contributor
timestamp: August 05, 2025, 10:08:58 pm
content: Quote from: tggzzz on August 05, 2025, 10:48:00 amExcellent question, and I hadn't thought about it before. It is the pressure relative to the ambient air pressure. I don't think the rules about feet or metres of 'head' apply to a sealed system, do they? I visualise a simple vertical pipe, closed at the top and bottom, filled completely with water. Assuming there is a tap at the bottom, opening it will release no water (ie zero pressure) unless the tap also lets air in.Interesting question and it needs thinking about!

author: Analog Kid
author_rank: Super Contributor
timestamp: August 05, 2025, 10:21:46 pm
content: Quote from: golden_labels on August 04, 2025, 06:57:03 pmMaybe they didn't really expect any replies to a plumbing question on an electronics forum ...

author: tggzzz
author_rank: Super Contributor
timestamp: August 05, 2025, 10:30:34 pm
content: Closed in normal operation, but not while venting gas (until water appeared) on the top floor. Never needed to release water at the bottom.I wouldvent as much gas as possible at the topclose ventallow water in at the bottom until pressure had increased to ~1barrevent at toprinse and repeat until water appeared at ventfinally increase the pressure to ~1barBetween 2 and 3 the pressure gauge indicated ~0bar, even though there was a column of water above it. above it.IIRC the expansion tank/bladder had to be reinflated regularly. I imagine a larger bladder would have been beneficial; don't know why there wasn't one.

author: coppercone2
author_rank: Super Contributor
timestamp: August 05, 2025, 11:06:47 pm
content: 'if you have access to a suspicious pipe you cannot shutoff then you can freeze it temporarily.If the noise stops after you freeze it it means its related

author: m k
author_rank: Super Contributor
timestamp: August 06, 2025, 01:39:31 pm
content: Quote from: tggzzz on August 05, 2025, 10:30:34 pmSo membrane(rubber?) is leaking?First stand still water is pressing.Then pump start pumping and pressure is not equal.If pump can't generate enough pressure the top of piping has gas.But lower routes are still generating some pre pump pressure.What defines an automatic rinsing?I've seen once some remnants of freely circulating central heating, three floors with logs.No radiators were present, but plumbing was considerable, regular hardware of today can't cope.Not exactly arm thick, but not much behind were those first pipes.If I remember correctly the topmost part of the system was freely breathing expansion vessel.

author: tggzzz
author_rank: Super Contributor
timestamp: August 06, 2025, 05:03:45 pm
content: Quote from: m k on August 06, 2025, 01:39:31 pmHouse was sold several years ago, andcompletelyrenovatedEverything was working normally; it was just the pressure reading that I cannot understand.

author: SteveThackery
author_rank: Super Contributor
timestamp: August 06, 2025, 09:14:59 pm
content: Quote from: tggzzz on August 05, 2025, 10:30:34 pmIn that case it is probably faulty. If the membrane gets a hole in it, air will mix with the water, circulate, and get bled out. Alternatively the water might absorb the air.If the membrane is OK, and the Schrader valve on the vessel is properly sealee, it should never need reinflating.

author: SteveThackery
author_rank: Super Contributor
timestamp: August 06, 2025, 09:17:53 pm
content: Quote from: tggzzz on August 06, 2025, 05:03:45 pmAs I mentioned earlier, I think the water column has to be open at the top for it to generate a head of pressure. If it's sealed at the top, like a central heating circuit, then no head of pressure will show on the gauge.

author: tggzzz
author_rank: Super Contributor
timestamp: August 06, 2025, 11:04:01 pm
content: Quote from: SteveThackery on August 06, 2025, 09:17:53 pmIf there is 32ft head of water, how can the pressure at the bottom be less than 1 bar?If you heat the water and it is unsealed, the water level will rise a little due to water expansion, and that will increase the pressure slightly.If you heat the water and it is sealed, then the pressure will increase a lot because there is no room for the water to expand.PV/T=constant

author: tggzzz
author_rank: Super Contributor
timestamp: August 06, 2025, 11:05:21 pm
content: Quote from: SteveThackery on August 06, 2025, 09:14:59 pmMy recollection is that the membrane was either replaced or reinflated more than once. I presume that it was simply too small for the house.

author: SteveThackery
author_rank: Super Contributor
timestamp: August 07, 2025, 10:46:59 am
content: Quote from: tggzzz on August 06, 2025, 11:04:01 pmBecause the water is "held up" by the vacuum that would have to appear at the top in order for water to flow into the pressure gauge.It's easier to imagine a vertical fully sealed tube filled completely with water (radiators and stuff complicate matters). Make a small hole in the bottom of the tube: no water will flow out unless you let air in to displace it. Put your finger over the small hole - you will feel no pressure. The column of water is supported by the vacuum at the top that would have to appear for water to flow out. The water is "hanging" on the vacuum, if you like. More correctly, air pressure from the environment is pushing the column of water upwards.Sorry, @tggzzz, that's the best I can do!

author: tggzzz
author_rank: Super Contributor
timestamp: August 07, 2025, 04:03:54 pm
content: Quote from: SteveThackery on August 07, 2025, 10:46:59 amSuch a vacuum could only support 32ft of water, but the house is much higher than that. Plus when the top vent is open there is no vacuum and I'm allowing more mains water in while bleeding the radiators.No, I don't understand the pressure gauge either, nor do the heating technicians!

author: Sorama
author_rank: Frequent Contributor
timestamp: August 07, 2025, 07:03:15 pm
content: Quote from: tggzzz on August 07, 2025, 04:03:54 pmmains water is not connected to top vent (again, it's a closed circuit).

author: tggzzz
author_rank: Super Contributor
timestamp: August 07, 2025, 08:43:02 pm
content: Quote from: Sorama on August 07, 2025, 07:03:15 pmIt is when you are refilling radiators with water from the mains. When refilled you close the inlet valve to isolate it again.That's SOP: see the boiler operation manual.

author: Sorama
author_rank: Frequent Contributor
timestamp: August 07, 2025, 09:43:43 pm
content: Quote from: tggzzz on August 07, 2025, 08:43:02 pmyes, but why do you mention the top vent?There is no vent at all wrt water mains.

author: SteveThackery
author_rank: Super Contributor
timestamp: August 07, 2025, 09:55:39 pm
content: Quote from: tggzzz on August 07, 2025, 04:03:54 pmWell of course the technicians don't understand it - you must have met a few by now and arrived at a view of their intellectual prowess.When the column of water is greater than 32ft then of course a vacuum will be drawn at the top, and then the pressure gauge shows the total head minus one atmosphere. However, when you are bleeding the radiators you have connected the mains water to the bottom of heating circuit and the atmosphere to the top. The mains water is at a higher pressure than the heating circuit (it must be, or it wouldn't bleed it). That situation only exists whilst you are bleeding it.Tell you what, @tggzzz, instead of hoping other people will explain it to you, and finding them lacking, how about you put the effort in yourself? You're a smart guy - smarter than the average heating tech - and you have a good knowledge of the relevant physics, so sit yourself down with a pencil, paper and pad and draw it out. Work through the physics and you will arrive at the answer.

author: tggzzz
author_rank: Super Contributor
timestamp: August 07, 2025, 10:07:29 pm
content: Quote from: SteveThackery on August 07, 2025, 09:55:39 pmI've had a relatively cursory look for the answer, and not found sufficient information.A schematic of a boiler would be a good start, but the manuals I've found are "which pipes to connect during installation" and "if you see this error code, do that".I don't have the inclination to hunt for the equivalent of "how to design a PSU", and learn the characteristics of a BJT vs MOSFET.

author: MrAl
author_rank: Super Contributor
timestamp: August 08, 2025, 08:37:14 am
content: Quote from: Sorama on August 05, 2025, 09:04:00 amI don't think you have experience with every hot water heating system under the sun. I say that because I know of two systems in use today that do have a cold water feed into the hot water heating system (this is not for hot tap water only for heating). They use baseboard heater cores with copper pipes and aluminum fins. Normally the hot water flows though the pipes and stays in the system, but even a tiny leak over time will drain any water system. Connecting to the mains water feed means this won't happen, but with a large leak of course could cause water damage.I'll repeat that I know of at least two systems in homes that work the way I said they do, they have a direct and constant connection to the mains water, the cold side not the hot side from the hot water heater which is a different system just for getting hot tap water.I might even have a picture of one of those systems where you can see the cold water feed and there is a valve you can close if something goes wrong with the heater and has to be fixed.

author: Sorama
author_rank: Frequent Contributor
timestamp: August 08, 2025, 09:40:33 am
content: Quote from: MrAl on August 08, 2025, 08:37:14 amYou obviously don’t know a damn thing how these sun collectors work.Please, don’t tell me how to do my job.

author: SteveThackery
author_rank: Super Contributor
timestamp: August 08, 2025, 09:40:45 am
content: Quote from: MrAl on August 08, 2025, 08:37:14 amThis surprises me, because here in the UK, at least, we use corrosion inhibitor in the sealed heating circuit. If there was a connection between the heating circuit and the cold water mains, itcouldresult in corrosion inhibitor getting into the drinking water, and then the resultant corrosion in the radiators.Quote from: MrAl on August 08, 2025, 08:37:14 amAh, but that's different. All 'combi' boilers have a valved connection between the mains cold water and the heating circuit. It's called the 'filling loop'. However, it should beclosedin normal use, not open. Are you sure the systems you have in mind are supposed to run with that valve open? I'd bereallysurprised.

author: Sorama
author_rank: Frequent Contributor
timestamp: August 08, 2025, 10:00:21 am
content: Quote from: SteveThackery on August 08, 2025, 09:40:45 amExactly.

author: MrAl
author_rank: Super Contributor
timestamp: August 08, 2025, 03:34:28 pm
content: Quote from: Sorama on August 08, 2025, 09:40:33 amYou are taking this too personally and not gleaning the meaning of my intent.I don't have to know how your sun collectors work because I am just telling you about a DIFFERENT system, and that should be obvious.Also, I NEVER force anyone to do anything, especially not on the web and even less in a forum where there should be free expression.You are under NO obligation to do anything I ask you to do, you have a free will so you are free to use it. Suggestions are just suggestions, and reports are just reports.If I told you to jump off a bridge you wouldn't do it, and I wouldn't blame you for not doing itI would never tell you that though but I would tell you about other systems that I have experience with. If they don't help you then you don't have to worry about it. You have to do what YOU think is best.

author: MrAl
author_rank: Super Contributor
timestamp: August 08, 2025, 03:44:36 pm
content: Quote from: SteveThackery on August 08, 2025, 09:40:45 amHi there,Well it is possible that they do some systems like that here too, but apparently not every system because the ones I have seen are as I described exactly. One system was upgraded significantly too and the water mains stayed connected and the plumber left the valve open. I'll try to dig up a picture, but it would just show a mains water line running into the pipes of the hot water heater.There is also the possibility of a check value to prevent back water flow. I didn't think to check for that though because we never had a big problem with any of it. I know we did not use any corrosion prevention stuff though. I also lived in both the homes I described.There is also the possibility that these are much older systems. However, we can learn more by doing a search for "Why some hot water heating systems have a direct connection to the water mains". Some keep the valve closed and rely on manual refilling, while others stay open.This reminds me of an automobile cooling system. It is closed, but sometimes needs water to be added.I encourage anyone who doesn't like hearing this to just go on with whatever they believe and there's no problem with that.

author: tggzzz
author_rank: Super Contributor
timestamp: August 08, 2025, 04:12:10 pm
content: My mains supply is ~7 bar. If that was left connected to the boiler, the overpressure valve would open at ~3 bar!

author: SteveThackery
author_rank: Super Contributor
timestamp: August 08, 2025, 04:24:45 pm
content: Quote from: MrAl on August 08, 2025, 03:44:36 pmOK, but can you see my problem? If there is a permanent connection between the heating circuit and the mains water, then the water you drink might have been around the radiators a few times, picking up rust and scum. Surely you would agree that such a thing would be disgusting and seems most unlikely. Yes?Could you address that specific point? I'm just trying to understand how the system you describe works.

author: SteveThackery
author_rank: Super Contributor
timestamp: August 08, 2025, 04:30:15 pm
content: Also, respectfully, is it possible you are confusing the hot water system and the heating system?In a normal combi boiler installation, the hot water is fed directly from the mains water, through a heat exchanger in the boiler, and out to the hot water taps. So obviously the hot water system has an open connection to the mains water.But we are talking about the heating circuit, and this is the one I can't understand because a permanently open connection to the cold water mains is guaranteed to mix your drinking water with water that has been around the radiators.

author: m k
author_rank: Super Contributor
timestamp: August 09, 2025, 02:00:05 pm
content: Quote from: tggzzz on August 07, 2025, 04:03:54 pmResidual pressure?When pressure goes up it should also go up inside expansion vessel's gas volume.System has min - max pressure.Expansion vessel is keeping values in check, pressure compensation.If vessel is too small it can't cope with high pressure and over pressure valve releases some water.Next when min pressure situation happens the actual pressure is too low and somewhere so low that bubbles start emerging.After a pump is high pressure and before it low pressure.(NPSH)

author: MrAl
author_rank: Super Contributor
timestamp: August 10, 2025, 07:47:03 am
content: Quote from: SteveThackery on August 08, 2025, 04:24:45 pmYes I can see your problem, but can you see mine? This whole thing has been questioned as if it could never happen in a million years, yet I have seen two systems firsthand and had direct experience with both systems and described those systems. I explained that, but still there are questions about the validity. The only explanation I can think of is that some people have not had any experience with these systems so they believe it could not be possible, even though someone states that they had direct experience with them.Well, the other possibility is that we have learned that on the web a lot of information is not reliable at all. I myself also question some things I don't think are possible, but if someone insists then I give them the room they deserve. Still, it's an interesting subject I guess after all so still interesting to talk about.That said, I am posting a picture of the system. The pipe going straight up is the cold-water mains pipe that comes from the same main pipe as the cold water for sinks. The blue handle valve is the valve that can shut off the mains water feed in case of a bad water leak.As to the specific point, yes that would be gross ha ha and I'd hate to have that happen, and I actually did address this you may have missed it. I understand though because sometimes these threads get long and involved. We are not alone with our concerns too because apparently one of the plumbing codes is that there has to be a backflow preventer valve, the abbreviation is BBFP and that, from what I understand, stands for "Boiler Back Flow Preventer". Some have TWO check valves inside, not just one. The check valves only allow water flow in one direction ... a "water diode" as it were.So I think this should set it to rest, but anyone is free to look up that abbreviation as: "BBFP valve" and see that there are several types.Quote from: SteveThackery on August 08, 2025, 04:30:15 pmAlso respectfully, there is no way I would ever do that because I've worked on these systems myself although not all by myself (someone else with me). I am not a plumber though and do not profess to know everything about plumbing, but I have done some small work on these systems like replacing a hot water tank which is for the hot water feed not for the heater.As far as being guaranteed to mix drinking water with water that has been in the radiator for 10 years, the BBFP prevents that and that is what those valves are for. Also, I did not install the new updated system a rather large plumbing company did the work. There were three guys working on it ha ha.So now that we should have this issue cleared up, did I happen to mention yet that the sewer pipe from the toilet connects directly to the cold-water pipe? Just in case the city turns off the mains water we can still get drinking water after the toilet flushes.Now there is something that is completely unbelievable so I suggest that nobody should actually believe that one

author: Eassssse
author_rank: Newbie
timestamp: August 11, 2025, 01:06:29 am
content: Thanks so much for the advice! It really helped a lot! Unfortunately, I'm not an expert (and this is my first time dealing with something like this), so I ended up calling a plumber to come check and fix it (and he actually used the methods you suggested!). The inspection confirmed there’s definitely a leak, and now I’m thinking about bringing in someone more specialized to handle it. Thanks u again Sorama

author: Eassssse
author_rank: Newbie
timestamp: August 11, 2025, 01:17:10 am
content: Hi，Thanks for asking ! The house was built about 6 years ago, and I just moved in a year ago. The previous owner lived here for about 4-5 years. The pipes are mostly PVC from what I can tell, and I checked a few places before buying, so the pipes seemed to be in decent shape.The water meter is outside, near the property boundary, about 8 meters away from the house, with the pipe running from there.We do have a garden irrigation system that connects to the main water supply, but I didn’t notice any issues with it when I checked.

author: amyk
author_rank: Super Contributor
timestamp: August 11, 2025, 02:22:57 am
content: While the use of thermal cameras for locating wetness has already been mentioned, it's also worth noting that a very slight temperature difference may be noticeable on pipes in the path of the leak, as incoming mains water is normally below ambient temperature and even a slow (and definitely an audible) leak will cause a small "current" to flow. If the leak is in a hot water line, then the pipes leading towards it will be above ambient.A sufficiently sensitive pressure gauge measuring different points in the "circuit" may also indicate a slight pressure drop.

author: MrAl
author_rank: Super Contributor
timestamp: August 11, 2025, 05:09:22 am
content: That's not a bad idea if the leak is sufficient to cause a noticeable change in the temperature of the pipe. With very small leaks though I'm not sure.If it was enough of a leak, the cold water pipe would be colder and the hot water pipe would be hotter. Might be hard to detect a small change though.

author: wilfred
author_rank: Super Contributor
timestamp: August 11, 2025, 05:28:57 am
content: Quote from: MrAl on August 11, 2025, 05:09:22 amIt is easy to detect by hand feel the difference in temperature of a metal pipe if even a small leak is causing hot water to flow. I imagine a PVC pipe would be not so easy. But I don't know.

author: Poroit
author_rank: Frequent Contributor
timestamp: August 11, 2025, 06:15:16 am
content: If you can hear water flowing then that is a substantial leak.....$$$$Your piping is probably PEX with Crimp fittings.If you are happy that you have ruled out all items that could leak inside the house, then focus outside.Tree roots can crack piping so look for any trees, lawn areas that seem more happy than usual. Particularly the 8 metre run from the water meter to your house.Locate the Isolation Valve for your Garden Retic and see if shutting it off stops your water meter.

author: SteveThackery
author_rank: Super Contributor
timestamp: August 11, 2025, 09:03:00 am
content: Quote from: MrAl on August 10, 2025, 07:47:03 amThank you for such a comprehensive response. As I work to get my head around it, I can only think of one more question: my boiler has a pressure relief valve that opens when the pressure in the heating circuit exceeds 3 bar. The released water goes into the condensate drain. How does the system you describe handle the case where the mains water is higher than 3 bar pressure?

author: tggzzz
author_rank: Super Contributor
timestamp: August 11, 2025, 10:28:12 am
content: There seems to be a presumption that all installations are code-compliant, safe, sensible.That seems..... optimistic.

author: Haenk
author_rank: Super Contributor
timestamp: August 11, 2025, 11:36:31 am
content: +1 for the gas sniffer.+1 for IR, if hot water piping leaksHad both in our company building, the heating was leaking out massive amounts of water. We were able to find larger leaks with a FLIR, however the gas sniffer discovered the whole truth. We had to open the concrete flooring, only to discover the heating pipes had completely rotted away, at almost around the whole building. Those idiot builders back then put the insulation against moisture *on top* of the piping, exposing the piping to the moisture, instead of protecting it.

author: Stray Electron
author_rank: Super Contributor
timestamp: August 11, 2025, 12:56:24 pm
content: Quote from: BradC on August 04, 2025, 02:21:14 pmJust FWIW, I don't know about your country but all water heaters in the US have a pressure relief valve so they're not going to explode. They're required to have them in case the heater fails shorted and the heater never turns off and starts boiling water into steam and over pressurizes the tank. Every water heater that I've bought in the past 40+ years has come from the factory with a pressure relief valve already installed.I'm also a long time home owner and like Bill said, I'm a big believer in isolation valves. If I have to work on a plumbing circuit that doesn't have one, then I add a valve to it. Besides troubleshooting, it's dammed nice to be able to work on one part of the system without having to go outside and shut off the water to the entire house.

author: BILLPOD
author_rank: Frequent Contributor
timestamp: August 11, 2025, 01:11:46 pm
content: Eassssse, you have confused me: You say you called in a plumber, and he 'fixed it', then you say you are going to call in an 'expert'. What will the expert do that the plumber hasn't already accomplished?

author: MrAl
author_rank: Super Contributor
timestamp: August 11, 2025, 05:02:15 pm
content: Quote from: SteveThackery on August 11, 2025, 09:03:00 amHello again,Oh, you are welcome, and I think I understand now why people would question this.There is also a pressure regulator, and I did not realize that until you asked this question. It is after the BBFP valve.Also, the BBFP valve has a second fitting for an atmospheric 'outlet' that I only understand a little bit. If the two check valves fail, it lets water out to prevent backflow. The water would flow through a separate pipe that leads outside of the house. The pipe had to be about 10 or 12 feet long because the heater was inside the house not too close to an outside wall. I remember that part really good because before the upgrade, the pipe was only about 2 feet long and it emptied into a pan about 3 inches deep and maybe 2 feet by 3 feet. If there was more water output than that, it would overflow. The new plumbers knew what they were doing so they installed an actual pipe leading to the outside. The only thing I didn't like about that was if the pipe got some water in it and it froze up, would that block the water outlet. Apparently, it was ok because that never happened in some 10 years after the upgrade. I could still see a problem there though, like what would happen if there was a small water flow in a cold winter night, and it gradually froze up the end of the pipe. That would block it completely. I do not know if there was any protection for that I never saw anything that might provide that function.I actually did some plumbing work in the past but mostly small repair stuff. One house had a cold-water pipe burst because the heat was off during the winter (a house fire shut down the whole place). I just had to replace a small portion of the pipe with copper tubing and sweat fittings.Maybe a little related, I also fixed several automobile radiators when they leaked, but they only needed soldering. That was back when they were made of brass and/or copper.

author: SteveThackery
author_rank: Super Contributor
timestamp: August 11, 2025, 11:39:52 pm
content: Quote from: MrAl on August 11, 2025, 05:02:15 pmNot the same thing, I know, but I learned something new a few months ago. The condensate from my combi boiler would, left to its own devices, exit into the pipe taking it outside in a slow dribble. In freezing conditions it would definitely freeze up in the pipe. To avoid that the condensate is fed into an auto-syphon device. The water accumulates in the syphon until it is full. The syphon then "trips" and discharges the water into the exit pipe in one "slug", which travels through the pipe and out, too quickly to freeze.I thought it was quite clever - never seen one before. I expect you guys know all about them.

author: tggzzz
author_rank: Super Contributor
timestamp: August 12, 2025, 06:57:23 am
content: Quote from: SteveThackery on August 11, 2025, 11:39:52 pmFrozen condensate dribbles are a standard failure mode, and the reason for specifying external pipes are surprisingly large diameter. Down in the south of the UK that's presumably sufficient. I haven't heard of the syphon mechanism, but it makes sense.

author: MrAl
author_rank: Super Contributor
timestamp: August 12, 2025, 12:00:38 pm
content: Quote from: SteveThackery on August 11, 2025, 11:39:52 pmYes that sounds interesting. I wonder if they worry that deep into it though because before this there was the drip 'pan' which although fairly large could be filled eventually, and there was no water alarm.Maybe they are banking on user observation and prevention. The user sees something wrong then calls somebody.Could it also be that they maintain a maintenance schedule that includes regular inspections.

author: MrAl
author_rank: Super Contributor
timestamp: August 12, 2025, 12:02:23 pm
content: Quote from: tggzzz on August 12, 2025, 06:57:23 amYeah that's what I was thinking about. They must rely on human intervention then in some manner or a maintenance schedule I guess, I never asked them but that's not impossible I might be able to remember the name of the last plumbing company that worked on it.

author: m k
author_rank: Super Contributor
timestamp: August 12, 2025, 12:31:01 pm
content: Quote from: tggzzz on August 12, 2025, 06:57:23 amSo open sewage, where's the closed one?Here the only one I can think of is HVAC.Rain water is not connected, it's from out and stays out, I guess HVAC is the same, cooling water is from ambient air.

author: tggzzz
author_rank: Super Contributor
timestamp: August 12, 2025, 12:48:46 pm
content: Quote from: m k on August 12, 2025, 12:31:01 pmInto the same place a the sink's waste water. Then a trap before going to the underground foul water pipe. Is that "open"?

author: m k
author_rank: Super Contributor
timestamp: August 13, 2025, 11:48:44 am
content: My impression was that external pipes and frozen concentrate means outside of the outer limit of the house and above the ground.

author: tggzzz
author_rank: Super Contributor
timestamp: August 13, 2025, 12:18:12 pm
content: Quote from: m k on August 13, 2025, 11:48:44 amYes.That pipe position is not unusual here.

author: m k
author_rank: Super Contributor
timestamp: August 13, 2025, 05:51:26 pm
content: So you're not categorizing that pipe as a sewer pipe?I wouldn't be surprised if here its type changes depending from which source the same water is coming.

author: tggzzz
author_rank: Super Contributor
timestamp: August 13, 2025, 06:46:05 pm
content: Quote from: m k on August 13, 2025, 05:51:26 pmI don't understand either of those paragraphs.If you looked at the outside of houses in my road you would see:condensate pipe going to an open drainsink outlet going to the same open drainbath outlet going to the same open draintoilet outlet downcomer going to underground pipeAnd the open drain (1,2,3) goes through a U-bend/trap into the underground pipe (4).

author: m k
author_rank: Super Contributor
timestamp: August 13, 2025, 07:32:56 pm
content: So 4. is a sewer pipe and it is open to outside.Where rain water goes, same place or elsewhere, always or when it likes?

author: tggzzz
author_rank: Super Contributor
timestamp: August 13, 2025, 08:04:28 pm
content: Quote from: m k on August 13, 2025, 07:32:56 pmThe sewer pipe is not open at ground level: there is a water trap preventing that. The top of the downcomer is open, above the eaves.Some rainwater goes to a soakaway, some down the garden, some probably to the sewer.

author: m k
author_rank: Super Contributor
timestamp: August 13, 2025, 08:31:16 pm
content: I think I get it now, the water trap is technically an odor lock.Here everything that can't freeze is deep under ground or inside in heated environment.Most all sewer pipes have their own odor locks at the beginning and main sewer is open.Our house has ten odor locked pipes and one without, the ventilation above the roof.

author: tggzzz
author_rank: Super Contributor
timestamp: August 13, 2025, 08:48:43 pm
content: Yes.Here the mains watersupplyhas to be underground to prevent freezing, and there are horizontal and vertical specifications about what underground means.I'm less clear about sewer specifications, but there will be a whole range of installations over the centuries, and they aren't going to be changed. Some, as in my late parents 1857 house, still make me shudder.

author: MrAl
author_rank: Super Contributor
timestamp: August 14, 2025, 01:30:01 pm
content: Quote from: tggzzz on August 13, 2025, 08:48:43 pmBack when I was very young I helped my father install an underground water pipe from the house to the garden, which was about 100 feet from the house. What a pain that was. The pipe had to be deeper than the frost line so there was a lot of digging. After that, the exit point at the end would still freeze up in the winter. We had one spigot fixture crack but the underground pipe survived.

author: tggzzz
author_rank: Super Contributor
timestamp: August 14, 2025, 02:57:14 pm
content: Quote from: MrAl on August 14, 2025, 01:30:01 pmThe regulations here are 750-1350mms below ground and insulation especially inside the building (variations for distances and subfloor construction)

author: Sorama
author_rank: Frequent Contributor
timestamp: August 14, 2025, 05:38:38 pm
content: Quote from: tggzzz on August 14, 2025, 02:57:14 pmOver here, pipes at the outside needs to be lower then 600mm.No ‘rules’ when inside.Actually? There are no rules here, just best practices.But when you go to court, these best practices often become rule.

author: m k
author_rank: Super Contributor
timestamp: August 14, 2025, 07:17:28 pm
content: Quote from: tggzzz on August 13, 2025, 08:48:43 pmNo wonder, for the old sewer.I'm lucky, I don't even smell the sewer as very bad odor, on the other hand, a bite of certain vegetable and I have an instant headache, or happened when I last bit one.Here water closet is pretty new thing.When first ones were constructed in Helsinki the whole system was banned, sewers were totally open and straight to the ocean.1920 Helsinki city and suburb housing survey has 669 water closets.The amount is marked to be less than 6%, so it's not apartment based, it's more like building based.Back then folks from lower level buildings had no water of their own, or just cold one and warm was floor based or less.If memory serves London invented high heels and real sewage system for the same reason.A bit later than the first round, with sandals and probably without high heels.Here clean water system goes so that the house has one pipe in, cold, it goes to the tap.Originally that was it, later it was divided, the new route is for a heater.Some times from that the heater water is divided again, new one is second cold.At this point the water is heated and hot water goes to the mixer with the second cold, hot water from mixer goes to tap.The mixer is because hot water is not allowed to be too hot, old systems can be without any safety.Finally tap mixer, if present, very rarely not, does its job and water comes out.Hot is made in many ways, but all potable waters have higher pressure than non-potable waters.So if potable pipe starts leaking it's leaking out, double fault is not specifically supported.But even if pipe is leaking and high pressure goes off it's still far from being really unhealthy.Central heating pipes are black iron, circulation is closed and oxygen consumed by the pipes.Generally all water based central heating systems have a combi boiler.After potable water is heated it can go to tap or a reservoir.Direct use has bad energy efficiency, so many have an electrical heater for summer water.Double fault, heat exchanger inside a circulation tank leaks and potable water pressure disappears.Water can continue flowing when circulation has pressure and it doesn't last long without automatic refilling.Many have manual refilling and alarm, so that oxygen in circulation water stays low.Usually overpressure has only a silent alarm, it's only harmful for the circulation system.One exception, rag heater.It's a styled pipe or thick loop of sorts where potable hot water is circulating.It needs a constant circulation, so it's only for bigger buildings.Nowadays people have lost some knowledge and some try to decrease the ambient summer temp of the space where that rag heater is by closing it.Apartments can't close hot water circulation of others, neither one rag heater has its own loop.So not long afterwards the maintenance will get a call.

author: tggzzz
author_rank: Super Contributor
timestamp: August 14, 2025, 07:39:22 pm
content: Quote from: m k on August 14, 2025, 07:17:28 pmThat house had some entertaining features...It was "Grade II" listed meaning that it required formal permission to change, and would have to be restored if any damage occurred. Scream.A inhabited basement surrounded by earth and, on two sides, external stone floors.The sewer went under the house, under one of the stone floors and into the sewer under the road.So did the water from the roof.Hence if the sewer became blocked it would have been necessary to locate the sewer in the street, and dig down at least 3m through the cobbled road surface.OK, you could in theory stop using the toilets and kitchen - but that would have left the water from the roof which could only have gone into the basement. And then the basement of the next house.Add elderly people and their helpers, and it wasn't too surprising that I once found the sewage pipe was distinctly backed up. Scream. Couldn't get a camera to turn through 90 degrees at the top of a "T" to go down the stem of the "T", and couldn't see anything in the murky water anyway. Scream.Fortunately after someone accidentally left a hot water tap running, I was surprised nothing had flooded - and that the backup had gone. Must have been soap/fat that was softened by the heat.Fortunately that's all behind me; the new owner spent best part of £500k getting it up to scratch.