Just found out our builder has damaged underground water pipe - help!

[anwensmummy]

We have recently had a garden office constructed, it was completed a month ago by a reputable company who did a wonderful job. Or so we thought until last night, when the local water company came round to check our drains, they said the people in the house behind ours have had sewage water flooding due to a blockage. They put cameras in the drain and it looks like one of the ground screws used to anchor our garden office into the ground might have damaged a drainage pipe that is under our garden, which serves our neighbour’s property. We didn’t know it was there, it’s not marked on any of the water and drainage plans we had when we bought the house in December 2020. They are doing more thorough investigations and a big clean-out today but we are going into an utter panic about all this. Garden rooms like ours don’t require planning permission, and the pipe is owned by the water company, but they said they would have the power to order us to fix the problem because it’s on our property. And if we didn’t do anything our neighbour’s house would end up flooded with raw sewage, which of course would be horrific. Of course we want to sort this out but we are really worried that it won’t be covered by our insurance. There’s also a guarantee insurance policy to cover the cost of replacing the garden office if it is faulty but it isn’t clear of this circumstance would be covered. Being the Easter bank holiday weekend we can’t contact the building company till Tuesday. My mind is spinning into orbit with awful fears of us losing a massive amount of money, and also of my beautiful garden office that’s only been operational for 28 days having to be knocked down! Has anyone had a similar scenario happen to them?

Just dig a hole under the garden room , the drain shouldn’t be too deep, remove the damaged pipe and ground anchor, replace the pipe , fill in the hole . Doesn’t sound like a big job

This should be quite straightforward. Contact the builders and they will need to come back out and fix it.

Technically, if the drain doesn’t serve your house but runs under your land it counts as a public drain and is the responsibility of the water company. However if you want to build an extension on or near a public sewer you need a build-over agreement, ie permission from the water company. In this case, you didn’t know there was a drain there so didn’t know to do this. Can you check the searches from when you bought the house? You may well have an indemnity policy on the drainage search that insures you against things like this.

The builder should be able to put it right, and claim on their own professional indemnity insurance. Though you might have to sue them for it.