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How to Repair a Sewer Pipe Under a Concrete Slab

This Old House plumbing and heating expert Richard Trethewey shows how to rescue a buried, root-clogged pipe, without digging up the whole site

In this video, This Old House plumbing and heating expert Richard Trethewey shows how to rescue a buried, root-clogged pipe, without digging up the whole site.

Steps for repairing a sewer pipe

  1. Insert a video inspection tool into the sewer pipe and look for evidence of tree roots growing inside the pipe.
  2. Attach a cutter head onto the end of an electric drain snake. Place the cutter head into the sewer pipe and turn on the drain snake's motor. Feed the spinning cutter head all the way through the pipe to cut away any roots.
  3. Mix two-part epoxy in a clean bucket using an electric drill and mixing paddle.
  4. Use a traffic cone as a funnel to pour the epoxy into the polyester pipe liner.
  5. Feed the liner between two steel rollers to evenly distribute the epoxy.
  6. Attach the end of the polyester pipe liner to a two-part air chamber, then turn on the airflow and feed the liner into the sewer pipe.
  7. Next, use the air chamber to force an inflatable rubber bladder through the inside of the previously installed liner.
  8. Replace the air chamber with a manifold, then attach a water hose to the manifold. Turn on the faucet and force cold water through the inside of the bladder. As the bladder fills with water it will expand the polyester liner.
  9. Wait approximately two hours until the epoxy has cured and the polyester liner has hardened into a rigid pipe.
  10. Drain the water from the pipe and pull out the bladder.