Cheap ways of detecting a PVC pipe underground ? - Page 1
Forum section: electronics / beginners

author: tigrou
author_rank: Regular Contributor
timestamp: March 25, 2025, 01:59:00 pm
content: Hello,I have a small (9 cm) PVC pipe going through a garden. It's max 30-50 cm deep. It's used to collect water during rain and it's "almost" clogged.Despite some efforts, I can't locate where it's located underground nor unclog it (there is probably roots, tree branches and LOT of crap, not just some mud).I can slide something into the tube (from one opening) up until logged section (the part I wanna locate). Between pipe and the ground is soil (not concrete).I'm looking for simple / cheap ways to find where it is. I took a looked online and professional devices (going very deep and working with all sorts of pipes including metal ones) range from 400$ to 2500$.I don't wanna spent so much and I'm looking for some other ways :Using a neodymium magnet + smartphone. I found out that smartphones can sense strong magnets from a distance. Unfortunately, it seems to be a limited range (probably 20 cm max). The fact it's located underground (with soil in between) will probably limit it even more.Using a fish tape + a coil (such as the ones in old radios) at one tip. Idea would be to inject a signal (which one ?) into the coil and sensing it from above (how ?).

author: JohanH
author_rank: Frequent Contributor
timestamp: March 25, 2025, 02:15:49 pm
content: You could rent some professional equipment.Is it deep? I don't know if this would work, but put a heating cable in the pipe, seal the opening and let it heat up long enough, use a thermal camera above ground.

author: Jeff1946
author_rank: Regular Contributor
timestamp: March 25, 2025, 02:23:33 pm
content: Fill tube with salty water and connect one end to ground and other to an audio osc. or speaker output from portable music player. Wind a coil and connect to headphones and listen for signal. No idea if this would work.

author: Kharn_the_Betrayer
author_rank: Contributor
timestamp: March 25, 2025, 02:33:20 pm
content: If you know the direction of the clog, and you can slide something in from one end up until the clog, then it seems to me the easiest way to locate it would be to slide something (probe) into the pipe until you hit the clog, mark the probe at the mouth of the pipe, remove the probe and measure how far it went down. Then measure that same distance from the mouth of the pipe in the direction of the clog, subtracting any elevation changes, and you should find it.

author: tigrou
author_rank: Regular Contributor
timestamp: March 25, 2025, 03:10:18 pm
content: Quote from: Kharn_the_Betrayer on March 25, 2025, 02:33:20 pmThat's what we did already. Then it give you some kind of circular arc perimeter where the pipe should be. We dig a 2m trench (30-40 cm deep) but couldn't locate it (it took a long time, especially there is small rocks from time to time making thing difficult to carve). Either it's deeper or further from the 2m distance we looked at.

author: perdrix
author_rank: Frequent Contributor
timestamp: March 25, 2025, 03:33:23 pm
content: Two bare brazing rods with a 90 degree bend about 100mm from the end.You can use them to dowse for the pipe. I didn't believe dowsing was valid until the guy from the water company did precisely that to find some pipes on my land. He then got me to find some of the pipes in the same way!David

author: tigrou
author_rank: Regular Contributor
timestamp: March 25, 2025, 03:34:49 pm
content: Quote from: perdrix on March 25, 2025, 03:33:23 pmIs there any scientific explanation of this ?

author: JohanH
author_rank: Frequent Contributor
timestamp: March 25, 2025, 03:42:02 pm
content: Quote from: tigrou on March 25, 2025, 03:34:49 pmNo

author: Zero999
author_rank: Super Contributor
timestamp: March 25, 2025, 03:46:03 pm
content: Quote from: tigrou on March 25, 2025, 03:34:49 pmThere isn't. Dowsing is woo woo, but a considerable minority of people on this forum appear to believe it works, including some seemingly knowledgeable, regular, posters.https://www.eevblog.com/forum/chat/dowsing/Don't try and convince them. It's a waste of time. If anything, it will make them more inclined to believe it, according to a poll, asking whether anyone changed their mind.https://www.eevblog.com/forum/chat/scientist-finds-uk-water-companies-use-_magic_-to-find-leaks/

author: JohanH
author_rank: Frequent Contributor
timestamp: March 25, 2025, 05:18:12 pm
content: Dowsing is more religion than engineering, so I'm astonished people in this forum suggest it as a solution. I'm sure there are more appropriate forums for nonsense and quackery.

author: themadhippy
author_rank: Super Contributor
timestamp: March 25, 2025, 05:34:36 pm
content: id shove a big lump of metal up the pipe and try a metal detector,or a stick of gelignite up it ,that'll might also dig the hole for ya.

author: Kharn_the_Betrayer
author_rank: Contributor
timestamp: March 25, 2025, 05:39:41 pm
content: Quote from: JohanH on March 25, 2025, 05:18:12 pmYou're telling me you don't pray to the Omnissiah when you have a new circuit design to test?Quote from: tigrou on March 25, 2025, 03:10:18 pmSeems to me like the next step is to determine exactly how deep the pipe goes, and whether it's level or on a decline.

author: Perkele
author_rank: Regular Contributor
timestamp: March 25, 2025, 05:49:22 pm
content: And what's the next step after you find the blockage location?For partial blockages I would take something like this:https://www.woodies.ie/drain-rods-accessories-drain-clearing-set-c-w-10-rods-4-tools-336182?objectId=36091&queryId=0d01a7a8ae2354210c8f7f3b869e0baa&indexName=prod_default_productsor this:https://www.diy.ie/departments/bailey-12-piece-drain-rod-set/5016729030490_BQ.prdYou'll probably find something similar in local shops.

author: fourfathom
author_rank: Super Contributor
timestamp: March 25, 2025, 06:19:18 pm
content: I kind of like the magnet idea -- attach it to the end of a fish tape. If you get someone to slowly feed the fish tape into the pipe, you can follow the magnet as it travels so you don't lose track of it. I suppose if the pipe is too deep then this won't work, but perhaps with a stack of magnets you could get a stronger field?I have one of those pipe-tracing probe/detectors, and these do work fairly well. Renting one may be your best option.

author: johansen
author_rank: Super Contributor
timestamp: March 25, 2025, 06:53:40 pm
content: I know a guy who builds the systems used to follow underground boring heads, magnetically. 512hz, half way between the 9th and 8th harmonic of the 60hz powerlines is the frequency. 3 or 6 solenoid coils are wound for the pickup and orientated in xyz, the software then reads the amplitude and phase of each pickup and calculates how far away you are from the boring head.you could attempt to build your own. you need a solenoid coil driven by an oscillator to fish down the pipe, and you simply wind a solenoid coil as a pickup. since you don't care about calculating the distance between the two, you simply have to walk around to get the signal the loudest.its an astronomically tiny signal btw. a spool of 30 gauge wire might work for a pickup coil. i wonder if you could directly feed it into a pezeo crystal earpiece.

author: calzap
author_rank: Frequent Contributor
timestamp: March 25, 2025, 08:13:11 pm
content: I’ve dealt with this problem more than once. Feed a loop of 12 AWG (2 mm) wire with insulation rated for wet locations as far as possible, sometimes using a fish tape. Then power a load of about 1500 W (a space heater) through the wire. I have an underground electrical cable detector to trace the wire. Have traced both 120 and 240 VAC. In the U.S., these detectors can be rented. Some detectors have a signal injector accessory, so no need to power the wire in that case.Mike

author: tigrou
author_rank: Regular Contributor
timestamp: March 25, 2025, 10:04:30 pm
content: Quote from: Perkele on March 25, 2025, 05:49:22 pmI have already tried (many times) with a high pressure head cleaner and cable cleaner like this :I use this in the past successfully (in other places) but it does not work here as it's probably filled with roots and wood.Quote from: calzap on March 25, 2025, 08:13:11 pmI like the idea. I will give it a try

author: radiolistener
author_rank: Super Contributor
timestamp: March 25, 2025, 11:28:19 pm
content: you can use 3D GPR (Ground Penetrating Radar) for that.

author: Ian.M
author_rank: Super Contributor
timestamp: March 26, 2025, 12:27:18 am
content: Fill pipe with nitro-glycerine'Fire in the hole'No more blockage (or pipe!)

author: ArchieAltz
author_rank: Contributor
timestamp: March 26, 2025, 12:39:41 am
content: Might be dumb but what about using a cheapo gps tracker and find it that way ?

author: coppercone2
author_rank: Super Contributor
timestamp: March 26, 2025, 03:38:32 am
content: I found a dowsing meter from a home owner too that worked in utilities. Same story, that it works.I like the salt water idea

author: pqass
author_rank: Super Contributor
timestamp: March 26, 2025, 03:40:07 am
content: How about using ablunt, long-ish (60cm - 1m) small diameter auger or spade bit (like those used to fish wire) and a cordless drill.Start from the pipes known location, gently drilling down until you feel a thud. Advance every meter or so to find it again. You may need poke around to account for misses/bends. Plot the path with flags as you go along. Connect the flags with a string of the same length as the drain snake inserted up to the clog. Voila, dig at the end of the string.You may end up with many holes but they're self-healing, fairly quick to drill (can use hose water to loosen the earth), and your lawn won't look like an archeological site.

author: JohanH
author_rank: Frequent Contributor
timestamp: March 26, 2025, 07:31:57 am
content: Quote from: ArchieAltz on March 26, 2025, 12:39:41 amGPS doesn't work well underground. But there are different kind of radio based trackers, e.g. for pets, but I don't know their frequency, how well they work through a layer of dirt. The cheap ones are definitely not that precise (10s of meters?). I'm not an expert in radio, but I would imagine, that the lower the frequency and better penetration, the harder it becomes to track the exact location.

author: Zero999
author_rank: Super Contributor
timestamp: March 26, 2025, 08:53:11 am
content: How about sound? Put your ear to the earth and tap it with a lump hammer. You might be able to hear a resonance when above the pipe/

author: tigrou
author_rank: Regular Contributor
timestamp: March 26, 2025, 10:13:25 am
content: Quote from: Zero999 on March 26, 2025, 08:53:11 amThat's not going to work as it's a flexible like this (without holes inside) :That's why it's so hard to remove branches and other things as it's not smooth inside of it.By the way, I found this on Amazon (about 70-100 EUR)Its a fish tape with signal + detectorThe inside looks really cheap :Some users found it useful some not.Alternative: professional equipment (170 EUR / day for rental, about 2000 EUR new)According to the datasheet it works in the following range : 8 / 33 kHz (normal) and 512 / 640 Hz (long distance). This looks similar to what johansen described.

author: Haenk
author_rank: Super Contributor
timestamp: March 26, 2025, 10:25:33 am
content: An easy way is to use some steel rod and poke into the ground, the tubing will make a "boing" sound (that's how I found some tubing in my garden).Or use an radio emitter with a long cable, push that into the tubing (maybe taped to a water hose) and a radio. I have used something similar (though ready-made) to find cable defects in the lawnmower signal wire.I also like the idea of using a declog tool for a power washer. I have one, but did not use it yet (it was very cheap).

author: Zenith
author_rank: Frequent Contributor
timestamp: March 26, 2025, 11:29:16 am
content: You must have access to one end. What about the other end? Does it go to a drain or soak away, or does it just disappear? It could easily be blocked with tree roots. If you could push a rod through, where would the material clogging it go?Do you suppose it runs in a straight line, or are there bends? Anything but gentle bends will make pushing anything through far harder, and will make it more likely that debris will be caught and build up. The requirement is not to find where it goes, so much as to clear it.If you want to trace it using RF, the first problem is to have the conductor/antenna going through it. The commercial systems for doing that have a reel of semi-rigid cable, which seems like a carefully selected material.I'd be inclined to hire/borrow a set of drain rods and try those. There are more sophisticated drain clearing tools with rotating heads, that cut up tree roots etc. Breaking up the material clogging the pipe is only part of the problem. Unless it's removed it will soon cause the problem to repeat.As for dowsing, the time I tried it I was over a water supply to a major city, which was three 3 metre pipes. I didn't notice anything. Maybe I wasn't doing it right, or just don't have that particular ability. I don't have much confidence in it.

author: golden_labels
author_rank: Super Contributor
timestamp: March 26, 2025, 12:17:08 pm
content: I find themadhippy’s idea the most reasonable. But, if not: is your location silent? 30–50 cm of ground should pass sound, in particular in low frequency range. If you can shove a small speaker and play loud drum/knocking sound from it, perhaps you could get the rough location of the pipe? Ears should work well enough the a detector. The low frequency used will not let you get the precise position, but I assume you want to dig a hole big enough to have convenient access to the pipe. Which should be enough to hit the pipe.Quote from: JohanH on March 25, 2025, 05:18:12 pmThis probably warrants its own thread, but some ancient religions losing in popularity shouldn’t be taken as a sign of human brain changing. Evolution of complex organisms doesn’t work that quick. It’s the same organ it has been when the solar deities rode their charriots on the sky and Perun was casting lightnings. And in many ways only slightly different than when you’d smack another ape with a stick.Quote from: Zenith on March 26, 2025, 11:29:16 amBut if you was that 1 in 100 people, who found a pipe, you’d never be convinced it was nothing more than a fluke.

author: Zero999
author_rank: Super Contributor
timestamp: March 26, 2025, 01:19:18 pm
content: Quote from: coppercone2 on March 26, 2025, 03:38:32 amIf it works, then it would go off all the time, since the human operator is mostly made of water.Just because a company used it, it doesn't mean it works. Many armies and security agencies used the ADE 651, until it was discovered to be ineffective.https://en.wikipedia.org/wiki/ADE_651

author: Zenith
author_rank: Frequent Contributor
timestamp: March 26, 2025, 01:45:12 pm
content: Quote from: golden_labels on March 26, 2025, 12:17:08 pmI'd be convinced if I, or someone else, could consistently find pipes or underground streams, with success significantly greater than chance.

author: tigrou
author_rank: Regular Contributor
timestamp: March 26, 2025, 02:05:10 pm
content: Quote from: Zenith on March 26, 2025, 11:29:16 amI have access to both ends.First one is the one that supposed to collect water from the ground (due to rains and such). There I can slide something about about 3m deep until it get blocked.The second one is connected to a sump (that is drained using another exit pipe). There I can put 4m (slightly more, yes sounds weird).There is probably a small (eg: not 90 degrees) bend somewhere between both ends.Neither are completely blocked. There is a little bit of water entering in and existing the other side. However if you put a hose and start filling water it get filled very quickly and then you need a LONG time to get cleared out (should be almost instantaneous).Pipe is either clogged OR crushed OR destroyed (because of roots, wood or mud).If it cannot get cleaned, solution is to either replace the pipe entirely or cut it in 2 pieces, unclog the mess and join it back using a sleeve.

author: Zenith
author_rank: Frequent Contributor
timestamp: March 26, 2025, 02:24:39 pm
content: If it's the sort of plastic drainage pipe I've seen, I doubt it's crushed. They are very strong.Since you have access to both ends, I'd hire some drainage rods and try clearing it with that. If you have tree roots which have grown into it, you won't clear them easily.

author: Ian.M
author_rank: Super Contributor
timestamp: March 26, 2025, 02:29:00 pm
content: PVC pipe that isn't draining a kitchen or bathroom (i.e. no fatbergs) doesn't usually block on its own. Unless some idiot has been pouring cement or similar stuff down it, or something has crawled in there and died, or the grate was missing so its now got a large piece of plastic or wood wedged at a bend, a blockage that doesn't wash away with a pressure washer and drain clearing hose, working from the down-stream end (i.e. isn't mud/silt) implies either a collapsed pipe or a break or crack with root penetration. Either means extensive digging, and as the whole pipe is of an age, if its got one crack, the rest of the pipe will be as brittle, so unless it goes under a concrete slab, if you don't want to have to fix it again next year, you might as well rip it all out and replace it all. If you are *really* lucky it might just be a failed joint due to soil settlement + root penetration at the joint, which *MAY* be worth fixing. Next step is probably see if you can borrow a drain camera and see if the blockage is visible.Quote from: tigrou on March 25, 2025, 03:10:18 pmP.S. I believe the minimum depth for drainage is supposed to be 600 mm soil surface to top of pipe. IIRC shallower pipes need to be capped with a concrete slab or similar.

author: Bafflegab
author_rank: Newbie
timestamp: March 26, 2025, 03:46:06 pm
content: Tape an Apple AirTag to the end of the tape. Use an iPhone to locate the tag.

author: tigrou
author_rank: Regular Contributor
timestamp: March 26, 2025, 04:00:50 pm
content: Quote from: Bafflegab on March 26, 2025, 03:46:06 pmSomebody tried and it's not so successful (I saw it few days already) :

author: Terry Bites
author_rank: Super Contributor
timestamp: March 26, 2025, 04:25:04 pm
content: Put a stake at the endpoints and buy some string?

author: halfwave
author_rank: Newbie
timestamp: March 26, 2025, 04:26:52 pm
content: Its already been suggested in one form or another but you need a locator. I've worked irrigation, we find control wires using this:https://armadatech.com/products/product/pro700/You can either rent one from a local supply house or find someone in irrigation to help. The trick with PVC pipe is to run a metal fish tape through the pipe and connect the signal generator to the fish. Locator will easily find the pipe. I did it all the time.

author: fourfathom
author_rank: Super Contributor
timestamp: March 26, 2025, 05:06:38 pm
content: Quote from: halfwave on March 26, 2025, 04:26:52 pmI have a similar unit and also use the fish-tape method with it. It does work well enough to be useful in tracing pipes that snake around underground. It takes some practice though.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 26, 2025, 05:08:21 pm
content: You know the elevation of the ends. If it is properly installed it should have a continuous slope between those points and you should thus be able to get the depth quite accurately at points in between. If you have done this and your existing trench didn't find it there are really only two possibilities. It was installed with a big sag in the middle and your clog is sediment that has gathered at the low point. That might have occurred if the original terrain had a dip and someone just laid the pipe before bringing in fill to set the current contour. Or there is a dogleg bend meaning your trench missed the pipe. In that case caught debris or tree roots are the more likely problem.You haven't mentioned the total distance covered. Is the 7 meters you can probe half the total distance, or some very different fraction? The answer can put some constraints on the geometry.In any case, the cheapest solution is more digging. You don't mention the tools you are using. A pick or mattock can make digging in the soil type you describe much easier than a shovel alone. A few weekends should the job. I have hand dug trenches up to 1.5 meters deep and shallower trenches 50 or more meters long with just a pick and shovel. The longer trenches were in soil much like you describe. It just takes some patience and is good for your health.The next cheapest option would be the finder from Amazon. It would probably work if the pipe doesn't have a big sag in the middle. I doubt if it would work in more than a meter of damp or otherwise conductive soil.Another option which may or not be available in your circumstance is renting an excavator. In my area rental of a small excavator is a couple hundred dollars for a partial day. If you have a vehicle that can tow the thing to your location and if you can get such a machine into your problem area it could be an option.

author: calzap
author_rank: Frequent Contributor
timestamp: March 26, 2025, 05:40:59 pm
content: Tracker I use is very similar to the Digicat. I don’t have a signal injector for this device and haven’t needed one. I’m usually trying to locate large wires running underground between panels in different buildings. It would be inconvenient and disruptive to try to send a signal through the wires anyway.Mike

author: fourfathom
author_rank: Super Contributor
timestamp: March 26, 2025, 05:59:07 pm
content: Quote from: calzap on March 26, 2025, 05:40:59 pmMy tracker has a clamp-on inductor for injecting a signal into any wires, as well as a clip-lead injector (ground + signal).

author: calzap
author_rank: Frequent Contributor
timestamp: March 26, 2025, 07:50:30 pm
content: Quote from: fourfathom on March 26, 2025, 05:59:07 pmI have an injector that I use with a smaller tracker for smaller wires in walls and ceilings. Very glad my larger tracker can detect underground wires running between building panels without needing a signal injector. Saves having to open a high amperage panel and messing with large, stiff wires. To be really safe when opening panels, power to the buildings should be shut down and locked/tagged off.Mike

author: MarkT
author_rank: Frequent Contributor
timestamp: March 26, 2025, 10:21:31 pm
content: Quote from: tigrou on March 25, 2025, 01:59:00 pmMagnetic field drops as 1 over distance cubed as magnets are dipoles, the bigger/longer the magnet the further it will reach, so perhaps extend a NdFeB magnet with some iron/steel rods at each end to improve the magnetic range - this just stretches the dipole longer.You could also try a standard metal detector if you can stuff metal objects down the pipe!Soil won't have any effect on the magnetic field unless its full of magnetic material.

author: tigrou
author_rank: Regular Contributor
timestamp: March 27, 2025, 05:22:12 pm
content: Quote from: calzap on March 25, 2025, 08:13:11 pmI have this device already, to detect mower cable cuts. It injects a signal trough the wire using the device on the left (one crocodile clip is connected to one end of the cable, the other clip goes to the ground). The device on the right is for detecting the signal itself.Would this device work with your trick (using device on the right alone) ?

author: calzap
author_rank: Frequent Contributor
timestamp: March 27, 2025, 08:46:22 pm
content: Quote from: tigrou on March 27, 2025, 05:22:12 pmWell, the setup with the wire and load looks right. But I can't say whether your tracker would be sensitive enough. But give it a try with the injector first. If that doesn't work, try the load. Be sure the load is powered via GFCI (RCD). I don't have that model of tracker. Even though I have a different brand of small tracker with signal injector accessory, I've never used it for underground detection because my larger one works so well with no need for an injector.Mike

author: Smokey
author_rank: Super Contributor
timestamp: March 27, 2025, 09:51:27 pm
content: Quote from: tigrou on March 25, 2025, 01:59:00 pmum... is $9 USD too much?https://www.harborfreight.com/27-in-round-nose-mini-shovel-with-comfort-grip-handle-64922.html?gStoreCode=577&gQT=1

author: Pid
author_rank: Newbie
timestamp: March 28, 2025, 04:23:20 am
content: Leave the original pipe in situ' buy if possible some secondhand solid pvc pipe which is easy to cut and join, hire a trencher.Use a water level between a couple of metal stakes with a string line to measure down from to maintain a gradient.For the water level an old hose pipe with a small section of clear pipe added at each end will do.

author: antenna
author_rank: Frequent Contributor
timestamp: March 28, 2025, 05:12:30 am
content: If you can get a strong neodymium magnet down there via snake, a good compass might pick it up.

author: tigrou
author_rank: Regular Contributor
timestamp: March 28, 2025, 08:51:02 am
content: Quote from: Smokey on March 27, 2025, 09:51:27 pmWe already spend a whole afternoon digging around the garden and making a 2-3m (30 cm deep) trench without success. It's really hard as there are grass to take care, grit and stones in the soil (blocking the shovel). I have a pick axe and lot of other things to dig but care must but be taken as I don't wanna damage the pipe.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 28, 2025, 09:04:12 am
content: Fill it with oxy-acetylene....

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 28, 2025, 11:05:33 am
content: I wouldn't worry too much about damaging the pipe with a pick or mattock. The broad end of a mattock is extremely unlikely to do serious damage, and worst case the pointed end will make a small puncture. It can be ignored, with the very real risk of future root penetration, or easily repaired with any number of materials.Even if you precisely locate the pipe you will almost surely have to dig it up to clear the clog unless you buy or rent specialist equipment.If the risk and labor is daunting, perhaps hiring a pro to do the job is appropriate.

author: tggzzz
author_rank: Super Contributor
timestamp: March 28, 2025, 11:24:18 am
content: Quote from: mikeselectricstuff on March 28, 2025, 09:04:12 amAs a kid I went to many lectures and demonstrations at the Royal Institution. One was a demonstration of the combustion of stoichiometric mixtures of several gasses with oxygen, culminating in acetylene+oxygen in a 1 pint glass milk bottle. Impressive, both on the eardrums and the multiple layers of protective devices around it. The milk bottle was nowhere to be found, but there was a heap of glasspowderDoubt they could do that nowadays

author: JustMeHere
author_rank: Frequent Contributor
timestamp: March 28, 2025, 11:59:13 am
content: Usually you can rent special purpose tools.Plan 2: find the tool on Ebay, buy it, use it, sell it on Ebay.

author: fourfathom
author_rank: Super Contributor
timestamp: March 29, 2025, 06:26:22 am
content: Quote from: CatalinaWOW on March 28, 2025, 11:05:33 amI don't know about that! I've cracked many buried PVC water pipes, and sliced through numerous buried polyethylene irrigation lines with a mattock. But a shovel is even more dangerous.

author: Haenk
author_rank: Super Contributor
timestamp: March 29, 2025, 04:08:41 pm
content: One thing comes to mind: The company that installed these very same drainage pipes in my garden covered the pipes in coco fibre mats. The holes in the drainage pipes will let sand etc. get into the pipes, clogging them. The mats will block the particles and keep the pipes clean. Though being natural fibres, they do hardly rot, even if buried, and will probably outlast me.So if you are redoing the piping, you might want to consider this.

author: johansen
author_rank: Super Contributor
timestamp: March 29, 2025, 07:13:55 pm
content: Quote from: fourfathom on March 29, 2025, 06:26:22 amI broke a 3/4" pvc schedule 40 water line with hardly a gentle touch. I knew the line was there, did not expect it to be only 8" deep in gravel.A friend of mine says he can feel his backhoe touch a 3/4” pvc pipe. I think he is imagining things.A 9cm pipe is 3.5 inches. At that diameter and thickness they are pretty tough.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 30, 2025, 03:34:29 am
content: Quote from: johansen on March 29, 2025, 07:13:55 pmThat has been my experience also.

author: Poroit
author_rank: Frequent Contributor
timestamp: March 30, 2025, 04:54:29 am
content: G'day tigrou,90mm pipe is normally Storm water pipe and it has thinner walls than Sewerage pipe.I have experienced both these types of pipes being cracked/crushed by tree roots over a period of time.(Attached)I assume this pipe connects to the guttering of your house to drain away rainwater.Does the pipe empty into Drain or a Soak well?I suggest you engage a Plumber who has an Inspection Camera to pinpont where the blockage is and then you decide how to repair it.If it has been underground for a long time it could be under some very big tree roots

author: tigrou
author_rank: Regular Contributor
timestamp: June 23, 2025, 11:32:41 am
content: Hello,I finally fixed the issue 3 months later (get delayed because of many reasons) using a Digitcat 500 (detector) and a cable :It's normally 195EUR / day (100+95 cable being rented separately) but got 30% and for two days long instead of one because of some mistake of their part , so I ended up paying 135 EUR instead of 390 EUR (best deal ever !).Those devices works incredibly well and where really needed in my case as there was multiple places to be found (and a bit of a mess to be honest). The cable is really long (30m) and will fit almost everywhere but it's also really stiff (on purpose) so it need a lot of care. I'm not sure what happen if you bend it to the extreme : does it shatter like glass or does it bend ?The only missing thing on the Digitcat is a compass (but with some experience you get around it). So other brands have one. You can get false positives when the device is not oriented correctly regarding the signal.

author: jonovid
author_rank: Super Contributor
timestamp: June 23, 2025, 02:06:44 pm
content: here is a 555 circuit you may like.

author: calzap
author_rank: Frequent Contributor
timestamp: June 23, 2025, 05:25:35 pm
content: Quote from: tigrou on June 23, 2025, 11:32:41 amGlad you got it done. The Digitcat 500 you used looks a lot like my old Radiodetection RD400. See pic. I’ve used the RD400 for years without a signal injector to trace power cables between buildings and buildings to pumps. Occasionally, put an energized cable into a plastic pipe to trace the pipe. Has always worked well. Be interesting to see a teardown on one of these. I assume the fin is filled with a large coil.Mike

author: tigrou
author_rank: Regular Contributor
timestamp: June 23, 2025, 08:45:07 pm
content: Quote from: calzap on June 23, 2025, 05:25:35 pmHere you can see what is inside a more modern version and get some explanation about how it works :https://www.subsurfacesolutions.com/single-post/2020/04/06/antenna-configuration-explainedTL;DRThere is 5 antennas :- The hollow round core antenna (center) is used for the compass.- The bottom horizontal antenna (right side) is the main one (ferrite core), it produces a "bell curve" signal.- The bottom vertical antenna (right side) is the opposite: the signal falls down to zero once you are close to the signal.- By using both vertical and horizontal antennas, it can detect the phase of the signal and tell if it's on the left side or right side of the signal. Both vertical and horizontal antennas receive a signal that have same horizontal component, but the vertical component has 180° phase shift.- The 2 antennas on the top (left side) are used for depth estimation : the distance between the bottom and top antennas is known (eg: 40 cm), as well as signal strength difference between top and bottom part, then it can deduce depth (distance from signal) by using a simple math formula.Quote from: jonovid on June 23, 2025, 02:06:44 pmWhile researching for solutions, I played around with some electronic circuits of my own.Using an inductor + some audio wave (as a signal generator), a ferrite core + coil (as an antenna), and a two stages op-amp amplifier circuit, I have been able to detect a signal quite precisely about 1 meter distance (would go trough thick walls of my flat without worry). Unfortunately, I have never been able to try it underground.

author: pardo-bsso
author_rank: Frequent Contributor
timestamp: June 25, 2025, 08:09:01 pm
content: I like the volume/on-off pot.Gives me warm memories.