Public sewer pipe within the boundaries of the property - diameter?

Section62

sad2k said:

Full image attached - I don't think there's a drain.

So if this does go into 65's garden does this make it any more problematic for me? (apart from having to relocate 2 of them if I were to build over) [to be honest we're unlikely to build an extension in any case here but I guess if we were to sell later, the buyers might want to]

It depends whether and how the pipes carry on into 65's property.

If they don't then it would appear you've got two private drains.

If they go to manholes in the back garden of 65 then you ought to be able to agree with TW to get the sewer diverted so the extension could be built. (but will involve ££££'s)

The real problem would be if 65 has in internal/external foul stack which goes straight into the manhole on 67's patio (i.e. out of the side, rather than to the rear). If it were done that way there's no way* of avoiding having 65's drainage under the extension, and that is unlikely to pass building regs.  (*unless a wide enough gap was left between the extension and 65's side wall)

sad2k

Section62 said:

The real problem would be if 65 has in internal/external foul stack which goes straight into the manhole on 67's patio (i.e. out of the side, rather than to the rear). If it were done that way there's no way* of avoiding having 65's drainage under the extension, and that is unlikely to pass building regs.  (*unless a wide enough gap was left between the extension and 65's side wall)

Thanks. In https://www.thameswater.co.uk/help/home-improvements/building-near-pipes they're talking about relocating a manhole instead (see image) - can this not be done?

Section62

sad2k said:

Section62 said:

The real problem would be if 65 has in internal/external foul stack which goes straight into the manhole on 67's patio (i.e. out of the side, rather than to the rear). If it were done that way there's no way* of avoiding having 65's drainage under the extension, and that is unlikely to pass building regs.  (*unless a wide enough gap was left between the extension and 65's side wall)

Thanks. In https://www.thameswater.co.uk/help/home-improvements/building-near-pipes they're talking about relocating a manhole instead (see image) - can this not be done?

It all depends on what pipes are actually there.  Without a drainage survey everything is guesswork.  But there are some possible layouts which I think would preclude building the optimum extension without a lot of additional expense (and cooperation from the neighbours).

If you really wanted to do an extension yourself it would be worth getting the survey and then seeing how the drainage might impact on whether or not an extension is feasible.  TW's rules and the building regulations are also subject to change, so what might be acceptable now may not be when you get round to doing the extension, or when you come to sell.

TBH I don't think this would be a barrier to a future sale.  Someone will be willing to buy - either without plans to extend, or without checking whether it is feasible before committing themselves to the purchase.