How to Seal a Sump Pump Basin

A sump pump basin is just one of several names referring to the container holding a sump pump. It is also called a sump pit, pump well or pump liner. The high-grade plastic basin sits about two feet underground and is a reservoir for ground or flood water. A float, moved by rising water seeping through the basin's porous wall, triggers the sump pump. Should a basin become a source of lethal radon gas emission, it will require sealing and a cover put in place. Basins also need sealing to prevent debris, insects, small pets and children falling into it.

Caulking All Exits

Seal a Sump Pump Basin
  1. Apply caulk around the exit point of each discharge pipe leading from the basin. Wipe any excess away. Allow to dry.

  2. Place caulk over the point where the vent pipe leaves the basin.

  3. Squeeze caulk around the electric cable's exit point.

Construct a Cover

  1. Place the wood on top of the basin.

  2. Make an outline of the basin by drawing around it with a pencil.

  3. Saw around the outline.

  4. Apply caulk to the rubber gasket. Place the gasket on the wood and press down firmly. Allow to dry.

  5. Cover the basin, with the rubber seal facing downwards and caulk around the cover making it airtight. Allow it to dry.


  • When dealing with caulk, always wear rubber gloves to prevent it touching your skin. It may cause irritation or contamination. Take care when dealing with electric equipment in damp or wet conditions. Cover plugs with plastic bags to prevent them getting wet.
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