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How to Install a Drain Pump for a Basement Sink

Draining water from below-grade plumbing with This Old House plumbing and heating expert Richard Trethewey

In this video, This Old House plumbing and heating expert Richard Trethewey drains water from below-grade plumbing.


1. Roll some plumber's putty between your hands to form a rope, then press it against the underside of the basket strainer.

2. Wrap Teflon tape around the threaded portion of the strainer.

3. Set the strainer into the drain hole in the sink, then from beneath the sink, slip onto the strainer the rubber gasket, fiber gasket and O-ring.

4. Thread the laundry tray pump onto the basket strainer; tighten it with pliers.

5. Wrap Teflon tape around the discharge port on the side of the pump. Then attach a threaded PVC adapter to the port.

6. Connect lengths of PVC pipe and elbows to extend the pump's drain line out of the sink cabinet. Glue the PVC parts together with PVC primer and cement.

7. Cut out a section of the existing drainpipe with a PVC saw.

8. Glue a PVC Y-fitting to the drainpipe. Join together the remaining joint in the drainpipe with a no-hub coupling.

9. Cut and dry-assemble PVC pipe and fittings to extend from the discharge port to the Y-fitting on the drainpipe.

10. Install a check valve to prevent water from draining back into the sink, and a ball valve to control the water flow.

11. Glue together all the PVC parts with PVC primer and cement.

12. Plug the pump's power cord into a GFCI-protected outlet, then turn on the sink's faucet.

13. Adjust the ball valve until the pump runs continuously.

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