Water Main Conduit

Hi everyone,

I'll be grateful for your advice. This house had an extension added to it and at that time, the opportunity was taken to upgrade the water main from 15mm copper to 25mm MDPE. This was laid around 700mm below the surface and enters the extension through a black conduit that goes through the wall and then turns upwards through the floor slab.

The pipe has foam lagging on it within the envelope of the house. The black conduit has never been closed off at the top. I don't think it was closed off well at the other end either. The guy who installed the pipe said he made a plastic cover which he stuck over the end of the entry to the conduit, and cut a hole in it for feeding the pipe through. He didn't use a proper, insertable cap on the outside, just a piece of round plastic he had cut out, enough to probably stop bugs getting in but not water. Too late to fix that now!

Having sent down my endoscopic camera, I have found that there is water at the bottom of the conduit, around the bend of the conduit (see picture), perhaps 55cm down from the floor level. I'm guessing this is ground water that has seeped in. Although it could possibly be condensation that has run down since the top of the pipe and the tap are usually wet, presumably because of the cold water running through them. I do not think the pipe is leaking.

A) is it normal to have some water at the bottom of a conduit like this, or is this cause for concern?

B) can you recommend any product I could pour down the conduit... something granular maybe that can find its way to the end, fill the spaces and then set into something impermeable that isn't corrosive to the pipe?

Thanks!

I wouldn’t worry or attempt to fix the other end, unless you reckon it’s a leak which you might be able to check if the water meter’s outside, and turn the internal stopcock off and see if it moves. Highly unlikely though if it’s a continuous piece of mdpe.

I’d just plug the top with a standard 110mm bung cut in half to fit. Personally I’d probably not even bother doing that and just expanding foam it. Or stuff some mineral wool in, whatever works

Signor Bob said:

A) is it normal to have some water at the bottom of a conduit like this, or is this cause for concern?

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I wouldn't bat an eye.

Signor Bob said:

B) can you recommend any product I could pour down the conduit.

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Squirt ex-foam in the top or fit a rubber pipe adaptor at each end.

Signor Bob said:

that isn't corrosive to the pipe?

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Its tough old stuff.