What is this pipe found when digging foundation? Is it considered public sewer?

Section62

user1168934 said:

Section62 said:

user1168934 said:

If it does turn out to be the sewer pipe, what steps do I need to take? Shall I ask the builders to make a manhole somewhere? - I don't currently have a manhole anywhere.

How do I find out if this belongs to the water/swerage company or me?

If it only serves your property it is yours - if it serves another property as well then it is probably a public sewer.

The drainage layout should really have been established/designed long before the builder started digging - the fact this pipe has come as a surprise suggests it hasn't.  If it were me I would not be happy having no access to the drain serving my toilet - I doubt building control would be either - assuming this is your private drain I'd suggest it needs to be re-routed so it goes to a manhole outside the footprint of the extension, and then connnects to the existing downstream drain (possibly with a second manhole there).  Discuss this with BC and see what they think.

All the drains are unmapped on any water/sewerage maps and they are not shown on any house documents that I have. How is the drainage layout established in the absence of any of these documents? (newbie question - sorry)

The easy way (if you have suitable manholes) is to get a (CCTV) drainage survey done.  If there aren't manholes then it means digging trial pits to find out where the pipes are.  TBH if you have a soil stack in the existing building then the builder should have expected there to be a drain somewhere, and advised you to get a survey/trial pit before starting the main construction work.  Now the footings for the extension have become one large trial pit.

user1168934 said:

We cannot see any drains going across to the neighbouring properties. There is just one straight pipe going toward the back of my garden, may be it connects to a pipe further down the garden that goes across to other properties.

You need to figure this out, as it will confirm the answer to whether the pipe in question is your private drain, or a public sewer.

user1168934 said:

Do I need to get permission from the water/sewerage company?

I read in the water/sewerage website FAQ that if the building inspector is happy then you don't need it - can someone confirm please.

The last thing I need is the building inspector not raising it now and when all the work is done they ask for a written consent from the sewerage company. On the other hand I don't want to mention it myself because then he will certainly say he wants it which will be another £700ish plus 21 days delay.

It depends whether the pipe is private or public, then the attitude of the sewerage company.

As a householder I would be really uncomfortable having a saltglaze(?) pipe encased in concrete buried in the foundations of my brand-new extension.  There's no flex on this kind of pipe, so when (not if) there is movement in the foundations as the build progresses, the pipe will be loaded and almost inevitably crack. A cracked pipe will allow sewage to drain into the ground under the floor and around the foundations - leaving you liable to both ground movement and sewage smells.

Building control are primarily interested in making sure those sort of problems are avoided - the public/private issue is less of a concern for them, as building over a public sewer is primarily a private issue between you and the water company.

However, a delay and some extra expense is nothing compared to dealing with sewage leaking into the ground under your extension - so raise it with BC and take their advice.  (also, going forward, take what the builder says with a pinch of salt as they could have predicted this issue and advised you better)

stuart45

I agree with Section62 about salt glazed pipes under the floor. Cracked pipes often cause blockages and the joints often leak after being in the ground for years. Putting a water test on them can easily blow the joints. Drainage is one area of the building trade where modern materials are superior to the old fashioned ones.
Now is the time to sort out the drainage if it is going to be done.