Drain lids in proposed extension site!?!

Discussion in 'Getting Started FAQ' started by BradleyMc, Aug 29, 2018.

  1. BradleyMc

    BradleyMc New Member


    Myself and my partner are in the process of buying our first house. The house we have identified is quite small however has a large garden, something we would like to exploit by installing a full width single story extension.

    Upon inspecting the site, it has become apparent that there are two Drain lids in the proposed area where we would like to construct the extension. I have contacted Thanes Water who are responsible for the drainage services within the area who have stated they are shared pipes (sewers). As we are an end of terraced house, the end which is closer to the main Thames water outlet we are confident everyone else’s and our waste runs through these pipes towards the road.

    I personally have no experience with drains so decided to turn to the internet. I have come across a few solutions some more costly then others and some actually not possible (double sealed lid in existing location with acces in house as Thanes Water do not allow this - conversation I had this morning with them).

    The solutions that I have conjured in my head are as follows, please bare in mind I have no drainage experience and this is all from online research:

    - Install a “Y” junction to take the inspection chamber further down the garden, away from the proposed site.

    - install a new independent pipe for our property Run this parallel to the existing pipe, this takes away the need for an inspection chamber as there is now no join?

    - write to the council (third party) and request we move the inspection chamber to the other side of our boundary.

    Ive decided to raise my concerns on this forum in hope of finding a cost effective or realistic solution. All opinions are welcome, positive or negative as well as insights from those with similar experiences and how you overcome them.

    Thanks in advance for taking the time to respond!
  2. chippie244

    chippie244 Well-Known Member

    Or buy a different house.
    rogerk101 and Heat like this.
  3. Heat

    Heat Well-Known Member

    You need an expert (builder or plumber exoerienced with sewer work will do) to take a look at it all and give you a definite answer.
    Whatever needs done to the sewer will require a plan and building control approval and inspection, especially on a shared sewer system.
    I also would try to buy another house tbh, but if you really want that house and sewer proves to be not impossible, then fine
  4. KIAB

    KIAB Well-Known Member

    Walk away & find another house.

    Not worth the hassle & grief to sort out,can/will end up costing a fortune to sort out.

    With them being Thames Water & public sewers, you could be looking at thousands & not hundreds to move them, if they can be moved.
    Last edited: Aug 30, 2018
    rogerk101 likes this.
  5. rogerk101

    rogerk101 Well-Known Member

    This is a legal / bureaucratic issue with Thames Water, and not a plumbing or building regs issue.
    Your conveyancing lawyer is usually responsible for pointing out issues with the deeds of the property you're looking to buy. He/she should have pointed out that the deeds contain least one easement, which provides the sewer supplier their public sewerage rights on the property. This is necessary because they use the property to convey waste from more than just the waste generated on the property ... it conveys waste from other neighbouring properties, making them public sewers.
    Even the world's most competent plumber is still just a plumber. Even the best intentioned building control office can only judge whether or not something adheres to building regulations. This is a matter for you (or your lawyer) and Thames Water.
    KIAB likes this.
  6. Penelopejean

    Penelopejean New Member

    Hello BradleyMc,
    I was wondering if you decided to buy that house? Last year my daughter bought a similar type ex-Local Authority house with a quite an old conservatory which had been built over her shared mains drain, probably illegally. The manhole cover is hidden under vinyl flooring. I don't think she'll have a chance to update the conservatory or ever build an extension but I think once the 2 bedroomed house is too small for them she will have to move. Enjoy the lovely large garden as she does in the meantime and look forward to buying a larger house later on.
    Good Luck Penny
  7. Richard_

    Richard_ Active Member

    It's not impossible to build over a sewer and other utilities but it would be ridiculously expensive for a small house. Also the water company retain the right to dig up the sewer which for a single storey extension would probably demolish it.

    That's a big reason why shopping centre layouts often follow the old street pattern for the walkways, or office developments are divided into blocks on the old street layout. It's just in case someone needs to dig a big hole to reach major utility routes.

    However.... there's always an alternate. If the sewer only serves a single set of terraces it'll be small enough to squeeze alongside the fence line with a clear strip a few metres wide for maintenance. The legal fees will run into thousands so unaffordable for a single storey extension.

    If the diversion liberated land for a 4 bed house then it might be worth it.

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