Buying house with public sewer manhole to rear - extension issue?

Rowan Case
last year


We're in the process of buying a house and our solicitors searches have revealed there's a public sewer manhole (Thames Water) in the rear garden. This wouldn't be too much of a concern, but we would like to add a single storey rear extension that would come within 3m of the manhole (it wouldn't build over it, but would probably come within a meter of it). It's currently concealed by a manhole cover tray in the existing brick patio.

Does anyone have any experience of a similar situation and any recommendations on how best to progress?

Is there anything we can do to ensure an extension is possible before purchasing the property?

Many thanks,


Comments (3)

  • Laura
    last year

    Not much help I suppose as our extension was built by the sellers, but our extension goes right up to the public sewer manhole in our garden. Extension stops around a foot before it, possibly less. The sewer itself runs parallel to the building so we haven’t built over it. Solicitors advised us when purchasing that if we wanted to extend further it would likely be possible but would have to seek permission from our water board.

    Rowan Case thanked Laura
  • Angie
    last year

    You’d need a build over agreement from Thames Water. In spite of the name, it applies if you’re planning to build close to the sewer, even if not actually building over it. If the house purchase depends on being able to extend it would be worth finding out whether such an agreement would be granted.
    We recently had to apply for one for our forthcoming extension as there is a shared sewer running alongside our house. In the end TW decided it wasn’t required and refunded our fee.
    There’s information about it on the Thames Water website.

    Rowan Case thanked Angie
  • PRO
    4 months ago
    last modified: 4 months ago

    I had a similar problem, but I can't suggest anything you can do. On the other hand, I collaborated with a lawyer who helped me with everything. I don't think we could've done anything without him. I tried looking for lawyers that we could work with at a distance. Luckily I found this fantastic platform It is an online platform created by super qualified lawyers and cand work online simultaneously. I'm sure if you share your story with them, they'll be able to give you a piece of advice.

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