Water supply above ground level

[egginstone]

Hello, please can I ask ... I need to replace my old iron water supply pipe - private supply, low pressure, about 1 bar. It's difficult to do it below ground level - removing the kitchen sink and cupboards, breaking the solid floor, and removing a drain that runs near the wall outside.

The wall is 600mm thick, undressed stone with rubble in the middle, no mortar, cement render outside. I'm considering running 25mm MDPE pipe in a stainless steel sleeve through the wall, with a box with a good thickness of insulation on the outside. There will be elbows immediately inside and outside. Given enough insulation I think it's unlikely the pipe will freeze, but not impossible. What normally happens to an MDPE pipe when it freezes? Does it expand without damage, or split, or is it likely to push off the elbows at the ends of the 600mm section through the wall? I don't mind too much if this happens on the outside end.

I'm also thinking of putting a stopcock above ground on the outside, within the insulation. Also a drain fitting. This is in addition to a stopcock inside. Is it worth paying the extra for an underground type stopcock?

Thanks for any comments, Eddie

 

[Adam Bunting]

you are going to have to turn the water off externally to be able to replace your supply pipe so if you haven't got an external stop valve you will need one fitting, either way this makes the extra stop tap pointless. As far as I'm aware your not allowed to terminate a supply pipe externally, it's supposed to be a minimum of 750mm deep, must terminate inside the building and be insulated as it starts to rise as it comes into the property.

 

[lame plumber]

being its a private supply, it will be hard for a water supplier to enforce their rules! just be aware the risk of freezing is high and youd be better off obeying the regs in the long term to ensure a secure supply. Being you have a small stone and rubble wall you probably wont have any foundations to speak of so get yer spade out and dig in under your wall and run it in properly, its what we do all the time. Just wait till you have to start pushing soil pipe through your walls, thats will be hard work in comparison

 

[welly2510]

I take it your on about running a new supply underground then bringing the water main up the outside wall and through into house, if so check out the groundbreaker water meter box. Its insulated and has a stoptap in already, you can also get pre made pipes to go through wall.

 

[egginstone]

Many thanks for replies, and I appreciate your taking the trouble.

Adam - at the moment I disconnect an underground coupling further up the garden and block the pipe with a broom handle - or drain the tank. Thinking behind the outside stopcock is that it (might) allow turning off the water if there's a problem upstream of the inside stopcock.

lame plumber - I take the point about digging out but it would be very disruptive. The kitchen would be out of use and I'd have to make rather a mess of the solid floor. There's also a drain outside that would need to be removed and replaced as it's in the way.

welly2510 - thanks for that, and I see the insulated ducting on the same page of the catalogue, might be neat.

Please can I ask for views on a bit more detail. There are some photos of the inside and outside on the link below. Also sketches. I could tolerate a leak outside but of course want to avoid one inside. How does a stainless steel pipe through the wall sound? I can get 22mm with 2mm wall thickness. Would it work ok with 22mm brass fittings? It would have a T on the outside, with the top of the T in line with the pipe. Supply on the stem of the T. A short length of MDPE pipe connected to the other end of the top of the T, in line with the stainless steel (see sketch).

The idea is that if the stainless pipe freezes the worst it does is expand or damage the plastic pipe, so the leak is outside. I don't know how pipes behave when they freeze. Of course it would be insulated. Any views on this please?

There are some photos of sketches and site but it won't let me post them. Is there a way to do this? I have to go out so won't be able to acknowledge replies immediately.
Eddie

 

[chris watkins]

Groundbreaker

As welly suggests check out these they do a range of products that may suit your needs.

The work on a private water supply is covered by these Reg's
[DLMURL]http://www.privatewatersupplies.gov.uk/private_water/files/TechnicalSpec.pdf#page=580[/DLMURL]

 

[egginstone]

Thanks for that Chris. There's a lot in that document and I'll have a more careful look through it.

To distill my question to the minimum, I think it's this: if a pipe through the wall freezes in spite of the insulation, what's the best way to avoid a leak inside the kitchen?

The pipe through the wall would be inside a steel sleeve (say 26mm bore). It would have an elbow inside and out, close to the wall. Would 25mm MDPE pipe burst or push off the elbows if it froze solid? Would 22mm stainless steel be better or worse for this?

Eddie

 

[stevetheplumber]

best thing would be to trace heat it not exspensive and would prevent it freezing

 

[lame plumber]

if the pipe was buried and came up in the house as per regs it wouldnt freeze!

 

[kris]

Hi egginstone obviously the guys are explaining the right way to do it but you dont want disruption to your kitchen and thats understandable these guys are like myself its always better to do it right if possible, do you have a utility room nearhand that you could take your new main into the house thus properly underground and have your new stopcock in the utility room (connecting to the cold water in utility providing pipe sizes is ok there)

 

[chris watkins]

The simple answer to your questions is the a non-metallic pipe would be better than metal one but for a plumber that is not the real issue we (as you can see from the responses) are focused on not allowing it to freeze in the first place.

Forget the possible damage that may be caused (& I doubt it would burst if it came out of the ground & went straight into the heated building) you would have a loss of water supply, a far more inconvenient situation.

The best advise now is to employ a professional who will way up all the different pros & cons along with possible routes & solutions including protection to stop it causing you problems, even if you still do the bulk of the work to replace the pipes.

 

[Ermintrude]

U can lagg it in duct if it's not practical to meet the Bylaws standard distance requirement

 

[Ch4 plumbing]

If you use mdpe make sure you sleeve it with a similar material through any cavity walls, if you use Steel There's a high possibility it will wear the pipe and cause a leak.

 

[lame plumber]

his walls are small stone n rubble ones with multiple cavities , does that make a difference

 

[egginstone]

Thanks for replies again. The kitchen is the nearest point, and all the floors are solid. It's a surface supply so we can fill a bucket if necessary. It's clear I'm trying to do something that's not in line with normal practice, so the cautions are making me wary.

If it's feasible when drilling I'll make a hole through the wall that will take a trace heater or a cable. In any case there will be a large box on the outside filled with insulation.

Through the wall it looks like either MDPE, sleeved; or stainless steel with some plastic on the outside to fail, so as to avoid a leak on the inside.

One question on detail: if using stainless steel, is it better to transition to copper with a brass fitting on a ss pipe, or a ss fitting on a copper pipe?

I'm going to do some tests on ss and plastic pipe and fittings, and am negotiating use of the freezer. Further advice and comments are welcome, and I'll post back with anything from the tests that seems of interest.

 

[Worcester]

A fitting is more likely to fail than a pipe, from a prcatical point of view (And i'll probably get shot down here as we very very rarely ever topuch the supply pipe in what we do, so it's not our area of expertise) why not use a pre-insulate pipe (rehau or watts - give the guys at Valeflex a call Microflex corrosion resistant, flexible, transport pipe )

We use preinsulated all the time when we have biomass boilers in garages and outhouses, and then bury it



Any outside valves.stopcock, you can make your own insulated cover for. Wrap it in polythene, put a box (2 x icecream containers with gaffer tape)) around it, fill with expanding foam, when set cut in half along the join betwenn the two ice cream containers - voila a custom fitting valve insulation. hold it back on with a couple of long tie wraps.

 

[Killy Bing]

WATER - METERS & BOXES

Bottom of the page sir for the beasty insulation