Neighbours drains and subsidence

ohdarn

Hello everyone, this is something of a hypothetical question, but I wanted to be prepared in case the worst case scenario occurs (and sorry this is a bit long winded).

We're in a detached Edwardian house and we've noticed cracks forming in an archway in our hallway. 

The archway is supporting walls above it so we took off the plaster to find that the arch itself has failed and we're currently supporting it with an Acro prop. 

We had a structural engineer come and have a look at it and he suggests that it could be due to a drain at the front of our property possibly failing, and causing a small amount of movement in that corner of the building. 

It's a bit tricky to describe where the drain is but essentially the bungalow that's next door had a driveway that went straight from their garage down the side of our house, to the road.

But due to a deal struck by previous owners, the end of this drive was given to our property for off street parking in exchange for the end of our garden. This is where the drain is located, so it's in front and off to the side of our house a bit.

We're going to get a drain survey completed but we've only got a bit of the drain on our side. It then runs up the driveway of next door and by the side of our house so a lot of it belongs to them.

If we have a survey done and it turns out it's the drain on their side that's damaged, what do we do about fixing it, can we compel them to do it?

Do we claim on our insurance, but will that go down as a subsidence claim and scupper our chances of insurance for years?

Do we just pay to fix it ourselves? 

If it makes a difference, the bungalow next door is now owned by a healthcare charity so we have to contact their head office, there's no neighbours to actually talk to about it. 

Thanks for anyone info you can provide.

jonnydeppiwish!

Is it a sewer? Ie do both houses waste enter it, and if so, where? If it’s prior to the collapse then it’s possible it belongs to the water company and they’ll repair

fluffymuffy

Another way to describe it -

If someone else's waste is passing through a pipe on your land, then that's a Public Sewer and is the responsibility of the water company.

outtatune

And if you're not sure if it's a public sewer, call the water company anyway and they'll come round and tell you.