Supply pipe replacement with MDPE - check my plan! | Plumbing Jobs | The Job-board | Plumbers Forums
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Discuss Supply pipe replacement with MDPE - check my plan! in the Plumbing Jobs | The Job-board area at Plumbers Forums

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tommys

Hi, I'm a competent person by diy standards and would like to understand if there are any serious flaws in the following plan.

Currently the supply pipe comes from the water board's box and across the boundary in a 25mm MDPE blue pipe.
That pipe is then joined to the original lead pipe, which I wish to replace.
The lead pipe runs beneath concrete slabs in the back yard, entering the house via a hole the shape of a missing half brick in the footings of the kitchen wall.

I aim to lay 32mm MDPE in place of the lead pipe. Getting it through the tight bends needed to enter the property and rise directly up the wall it comes through will need to use compression elbows.

I understand that I will need to lag the pipe (and the elbows) as they enter the property (I cannot put the pipe 75cm away from an external wall, its just not an option). I dont see how I can construct a tubular sheath that will accommodate all of the z shape made by a pipe with two elbows but I will find some way to put the MDPE and insulation through an outer sheath as it passes into the building.
I am mildly surprised that it seems uncontroversial to use compression fittings in the trench, but I'm perhaps too cautious and it is common?
The termination inside the house will be from 32mm via a compression reducer to 1" bsp then to 28mm copper to a 28mm brass stopcock.
I was not sure if it is necessary to fit an non-return valve at any point in this arrangement.

So my questions are:
Is anything here wildly misguided?
Any problem with using compression elbows below ground level?
As this work is is entirely within my property boundary do I still need to get the go-ahead from the water board people (or a plumber with the rights to sign a job off)?
If I want the run of 32mm pipe all the way into the supply box (i.e. to replace the short 1m of 25mm pipe that runs from the box across the boundary and into my property) will that be a costly?

And finally a BIG whinge: Given all the standards which we should all respectfully conform to, accepting that subsoil freezing could occur above 75cm deep for example, then the backfilling done when the water board fitted my water meter, installed mdpe 25mm pipe across my boundary then joined it to lead, WELL! the backfill was sharp stones & concrete chips mixed in with clay soil, no sand anywhere, sharp stones right up against the newly installed pipe and surrounding the joint fitting between the mdpe and lead. I was not impressed. I quick n dirty job that was but no leaks at the joint I am pleased to report.

Thanks for your interest and time.
Tom
 
to meet water regs you should use a wras approved plumber, having said that most don't, I try to never use fittings below ground as they can fail so why risk it, but you can. otherwise crack on.
 
32mm pipe size, long service trench with machine excavation?
Locate all utilities, including neighbours, before you start. Hand dig to confirm and assume nothing.
 
Great advice, thanks.
Trench will be dug by hand and with care, after cutting slots in the concrete slabs, no diggers for me. The neighbour's services will be intact, I promise. I realise that I really don't have a clue where the gas and electricity services are laid. Sewer is more predictable because that stuff only runs downhill :) And the plot is on a hill.
Tom
 
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