Working with 25mm MDPE Pipework

[CHarr]

I have a new kitchen extension and I need to run a new water supply pipe to it, across my driveway and front garden, connecting to the existing 1/2" (not 15mm) copper pipe passing beneath a retaining garden wall adjacent to the pavement (where my water meter is situated).

I'm intending to use a single length of 25mm MDPE pipe, terminating in the kitchen with a stopcock, but I have a couple of questions:

I'll be digging a new trench across the garden and driveway. The existing supply pipe is not very deep in the ground. It runs a short distance across my front lawn from behind a retaining wall, and while it is about 450mm under the lawn, it is about 50mm ABOVE the level of the driveway it needs to cross. What is a sensible depth to dig a trench (ie how far beneath the finished surface) should the pipe run in the ground?

Once I have excavated and run the pipe, what would be the best type of fitting to connect new to old? I looked at the range of stuff in a local DIY shed, but they only do push-fit 25mm/15mm connectors, and I don't think I'd get a good reliable connection with 1/2" pipe, and doubt that such a fitting would be suitable for burying, anyway?

Will the pipe require any particular protection before back-filling the trench? I was wondering whether to use 10mm gravel, as I did for the underground drainage pipework, before reusing and compacting the excavated material.

 

[Madrab]

Water regs state that a water supply pipe should be at least 750mm below the surface and no more than 1350mm. Anywhere in that range will be fine.

You should be able to get a Plasson 25mm x 1/2" adapter.

Normally you would bed in sand and cover with pea gravel and then backfill with excavated material, just make sure no large pointed stones in the backfill until at least 300mm above pipe.

 

[denso13]

I was wondering whether to use 10mm gravel, as I did for the underground drainage pipework

Not required IMHO, it is used around drainage for a reason. Use sand or even fine soil with no stones in it.

 

[MANDATE]

I installed a 25mm MDPE about 4 years ago.
I used a stop cock in the kitchen with 25mm MDPE compression inlet and 15mm compression outlet. B & Q about £8.
Note: The 25mm plastic pipe needs a 'insert' fitting.
1/2 inch copper pipe is 1/2 bore.
15mm copper pipe is 15mm outside diameter so the difference between the two is insignificant. (just a few thousands of a inch)

 

[CHarr]

Does MDPE pipe require any protection from being covered by the concrete of a floor slab? The hardcore sub-base has already been well blinded with soft sand, so there are no sharp edges that could damage the pipework from below. The pipe seems very stiff and I don't think that there is any risk of the pipe collapsing under the pressure from 100mm of concrete before it goes off.

 

[GavThePlumber]

It can differ from region to region, BCOs round here want it in ducting, the price difference is a few pounds, so always best to do it that way regardless.

 

[CHarr]

It can differ from region to region, BCOs round here want it in ducting, the price difference is a few pounds, so always best to do it that way regardless.

How about forming conduit from inexpensive 32mm drain pipe?

 

[HERTS P&D]

See below:

http://www.draindepot.co.uk/index.a...Duct+Systems&gclid=CPzN6NrogrsCFQTItAodDTQAYw

Andy

 

[Agile]

It can differ from region to region, BCOs round here want it in ducting, the price difference is a few pounds, so always best to do it that way regardless.

According to the Water Regs trainer all mains water supply pipe needs to be "accessible"!

That requirement is achievable by putting the pipe in a duct from which it can be withdrawn!

So all BCOs should want it in ducting!

But all buried outdoor mains water should be inspected by the local water supplier ( unless fitted by a qualified installer ).

Tony

 

[CHarr]

It can differ from region to region, BCOs round here want it in ducting, the price difference is a few pounds, so always best to do it that way regardless.

According to the Water Regs trainer all mains water supply pipe needs to be "accessible"!

That requirement is achievable by putting the pipe in a duct from which it can be withdrawn!

So all BCOs should want it in ducting!

But all buried outdoor mains water should be inspected by the local water supplier ( unless fitted by a qualified installer ).

Tony

An installer holding what qualification?

 

[Agile]

Water Regs course and registered with them as an "approved water regs plumber"!

 

[CHarr]

Water Regs course and registered with them as an "approved water regs plumber"!

Another scare: I'm doing nothing, as far as I can see, that is notifiable under the Table to Reg 5.

 

[Agile]

This is from Severn Trent's web page:-

2.2 Water Supply (Water Fittings)
Regulations 1999

These Regulations are national requirements
for the design, installation and maintenance
of plumbing systems, water fittings and
water-using appliances. Their purpose is to
prevent misuse, waste, under consumption
or erroneous measurement of water and,
most importantly, to prevent contamination
of drinking water.

The Government requires water suppliers to
enforce the Regulations, therefore we will
undertake inspections of new and existing
installations to check that the regulations
are being met. Where breaches of the
Regulations are found, we will require them
to be remedied as soon as practicable.
Where breaches pose a risk to health,
the water supply to the premises may be
disconnected immediately to protect the
health of occupants or others fed from the
same public supply. It is a criminal offence to
breach the Regulations and offenders may
face prosecution.

 

[newbuildinstaller]

Iv got a water regs card....

Its my emergency ice scraper has no other use!!!!

 

[CHarr]

If Severn Trent do inspect work that they have been been notified of, fair enough: but I'm not doing notifiable work on my reading of the Regs. They won't know, and I already know that BCO isn't interested. BC won't inspect, again until the over-slab insulation is ready to cover, by which time whatever I have placed beneath the slab will be buried (hopefully, for a long time).

I can see the benefit of using conduit, and will. I've got polypipe conduit pipe for the underfloor H&C water pipework already, and it's no great expense to make it possible to remove the MDPE too.