From: trk@palm15.cray.com (Tim Kirby)
Subject: Re: seperate hot and cold water taps in the UK
X-Newsreader: TIN [version 1.1 PL6]
Date: 22 Jan 93 17:33:43 CST

"Nadine Smith" (nmsmith@sunflower.bio.indiana.edu) wrote:
: 
: 	Could someone please tell a confused American (no jokes, please!)
: 	why the hot and cold water taps are seperate in the UK?
: 	And why if there is only one faucet is the hot and cold
: 	water kept seperate until it comes out of the tap? 

I'm sure someone will have a more concise and meaningful explanation ... for
what it's worth, this is what I remember vaguly from a long way back ...

I seem to recall the separation is required for drinking water supplies; mixer
taps (faucets) that don't keep them apart are quite common in showers. As to
precisely *why* ... I suspect there may be a connection (sic) with the fact
that a tap in a house in the UK may be supplied from either

(1) The main (i.e. directly from the pipe that comes up from the ground)
    (At least they always used to ... are they still ?) 
    Such a supply is considered safe drinking water.

or

(2) From a storage tank in the (roof/loft/attic/whatever). The tank in the roof
    would be fed by the main via a ballcock (automatic valve that opens when
    the water level drops). This supply would be used to feed the hot water
    tank and usually the other taps in the bathroom. Because the water could
    be standing for a long time and all sorts of horrible contaminants could
    get into it (dead mice, perhaps ?) this water is not considered drinkable
    (I always wondered why Mum said not to drink from the bathroom tap ;-)
    Since the hot water comes from this supply, it is kept separate from the
    mains supply all the time - presumably to keep whatever nasty things that
    might be in the hot water from contaminating the drinking water.

OK, so that might be so much BS. I'm just repeating an explanation I was given
a long, long time ago that I never verified. It's also worth noting that
the water pressure from the main would probably be higher than the 'head'
provided by the tank in the roof, to if the mixer tap with a main and hot
supply had a common channel and were blocked, I suppose the main could force
it's way back up the hot supply. Sounds improbable, though - particularly
given the relatively low pressure traditionally found in British water mains
compared to the US (this is why the British don't have very good showers,
perhaps ?) ... the low pressure probably being due to the aged water pipes.

Of course, there are the gas heaters (traditionally an 'Ascot') which I think
connected to the water main and heated the water as it was used ... and there
are the latter day electric shower water heaters that function in a similar
fashion.

Oh, that's enough of this drivel. Let's wait for someone who really knows what
they're talking about. Any Building historians out there ?

Tim

--
Tim Kirby --------- Cray Research Inc., Eagan, MN, USA ----------- trk@cray.com
Disclaimer: I disclaim, therefore I am. Cray Research is not responsible for me,
my views or anything I say ............... They do, however, pay my mortgage ;-)
When all else fails, Immortality may always be assured by spectacular error(JKG)
Xref: sparky soc.culture.british:19327 alt.usage.english:11001