New internal MDPE water main, rules and regs

[duve4]

Hi,

I'm looking to replace my existing internal lead water main with an MDPE plastic version.

The section I wish to replace connects between the stop cock under my kitchen sink and another stop cock at the boundary wall in my cellar. Pipework upstream of this point I believe to be responsiblity of the water company (a job for a different day ).

The lead pipe runs for approx 5m along the wall of the cellar before disappearing through the wall, through the solid floor of my back room, through the kitchen's floor and emerging under my sink (total run length approx 20m).

I'm replacing the floor in the back room with a new slab / insulation etc and would like to take this opportunity to replace the lead main.

What regs do I have to follow when completing this job?

1) Does the pipe need to be in any form of armouring / larger pipe as it passes under the floor?

2) Does it need burying to any specific depth?

3) Any other recommendations?

Any advice would be appreciated.

Cheers

Dave

 

[chrishutt]

It's good practice to run the pipe in some sort of duct when buried in a solid floor. If you're using 25mm polythene (PE) this could probably run inside a length of 32mm poly (PE) or 32mm waste pipe (ABS or PP). You could alternatively use 22mm plastic (PEX or PB) pipe which has the same bore as 25mm poly. Otherwise it's just common sense - use supporting clips at say 1 metre intervals for the horizontal run. The tricky bit will be connecting to the existing lead pipe.

 

[Agile]

Oops!

Under the floor in an unheated area, the pipe has to be insulated to a high standard as well as being in a waterproof duct.

Furthermore it has to remain accessible! Although being in a duct where it can be pulled along is acceptable.

Normally needs to be in a 75 mm waste pipe for example.

Water regs etc,

Tony

 

[chrishutt]

As I understood it the buried pipe will be in the heated part of the house. I think insulation is only required if pipes are on or close to an external wall. At least if it's in a duct and bursts (extremely unlikely) it can be withdrawn and replaced.

 

[Agile]

If its under the ground floor surface then it would be classed as an unheated area.

Thats unless there is a substantial insulation laid UNDER the water pipe.

Tony

 

[chrishutt]

I'm replacing the floor in the back room with a new slab / insulation etc and would like to take this opportunity to replace the lead main.

It looks like the whole floor is going to be well insulated so a water pipe laid in the screed above the insulation would be fine. Even if it's under the insulation layer and away from external walls it will only be subject to ground temperatures rather than outdoor air temperatures so won't ever freeze.

 

[duve4]

Cheers for the advice guys.

The current plan was to run it through the new floor. The floor would be a new DPM, concrete, Insulation, Underfloor heating, Screed, Tiles.

I'd guess there were two options then, both options would have the pipe running through a second bigger dia pipe

1) Pass the pipe under the dpm and insulate it. What / how much insulation would be required? Do you know of any links with examples.

2) Put the insulation (above the DPM) at the bottom and pass the pipe through the concrete.

Any suggestions gents?

Cheers

Dave