Drains - legal obligation.

Assuming no other property involved, the link is theirs on their side of the boundary, public from the boundary onwards. Depending on the layout (i.e. how it ends up going through your basement) some parts may be yours alone.

Thanks, Andy. That adds confusion. So the likelihood is Thames will charge them at least part of the costs of fixing it?

If the fault is entirely within the section owned by the neighbour and not shared with anyone, the whole cost will be theirs. If it is entirely within the shared section, TW will pay.

If there is more than one problem, the neighbour will only pay for the non-shared section.

Thames Water inspected things this morning - when I was out.

The problem is entirely before the neighbour's drain join mine - they saw some rubble in the pipe linking us together. But no signs of collapse.

Yet they have accepted it is their problem.

They also lifted the manhole in my front garden - just before everything goes to the street drain. And said there were problems there. Dunno what - as I didn't see it.

I suspect they apply a degree of pragmatism. A minor problem a couple of feet upstream in a 'private' section of pipe, has the potential to spread and become a problem in 'their' part.

Funnily enough I caught Thames Water lifting their cover outside our house this afternoon, and the bod was poking a camera down it I took the opportunity to confirm with him where our pipe becomes 'his'. He confirmed at the point it passes under our fence.

BTW, there was no problem, he just was conducting a routine check, and said everything was looking nice and clear. Clearly they have got time on their hands at present !

It may be that another house also shares that link.

I have a link from the next house to my drain, that I only found was there because water was running down my drain and I knew I had nothing going into it at the time!

That one one is definitely shared and theirs, from what you have said.

Definitely not. All semis this side of the road, and all the same. Nearest house to the back a very long way away - due to 'their' road doing a right angle bend, So my back garden backs onto the side of their (large) one.

Yes - I'd guess they'd have liked to look at the one in the back garden, but near impossible to access unless I'm there to let them.

The one in the front has got a special name - which I've forgotten. It includes a one way flap to stop the street drains coming into the house drains. And I'm fairly certain that has rusted away. But not had a problem with it.

Non-return valve?

I think that type of manhole has a special name - perhaps that of the company etc who invented it?