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Discuss Extending underfloor waste pipe in the Plumbing Forum area at

  1. Oj01

    Oj01 New Member


    I currently have a downstairs toilet that drops into a waste pipe that exits through the wall and into an inspection chamber.

    I need to extend the underfloor waste pipe to the next room for a new kitchen. As I am digging up the floor and re-doing the bathroom is like to confirm the best practice for connecting to the underfloor pipe.

    Is it okay to leave the pipe in position, use a 87.5 T piece placed with the T vertical, drop the toilet into this and carry through to the kitchen.

    Or is it better to drop from the toilet to a swept bend, and connect to a 45 degree Y connector placed horizontally? With the other leg carrying through to the kitchen

  2. CBW1982

    CBW1982 GSR Top Contributor!!

    I’d possibly go with option 1. Just be sure to use underground pipe and connections. Also make sure your sweep on the tee is in correct location.
  3. chris watkins

    chris watkins Plumber

    • Agree Agree x 1
  4. Oj01

    Oj01 New Member

  5. Craig Watson

    Craig Watson Plumber GSR Top Contributor!!

    As you are digging up the floor and altering the drainage you should be contacting building control. They will tell you what you can and can't do.
    • Agree Agree x 2
  6. CBW1982

    CBW1982 GSR Top Contributor!!

    It might now actually be the local sewage undertaker (e.g local water undertaker) as they now have some responsibility for drains and their connections.
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