• In this video, This Old House plumbing and heating expert Richard Trethewey shows how to keep a basement dry—even when the power goes out.

    Steps:
    1. Unplug, disconnect and remove the old sump pump from the sump pit.
    2. Apply Teflon tape to the threads on a check valve, then tighten the valve onto side of new 110-volt sump pump.
    3. Wrap Teflon tape around the threads of the battery-powered pump, then tighten the battery-powered pump onto the check valve. Set both pumps into the sump pit.
    4. Cut 1½-inch-diameter PVC pipe to length to form discharge pipe. Glue together PVC pipe and fittings and connect to existing discharge pipe with stainless steel hose clamps and rubber connector.
    5. Set deep-cycle 12-volt marine battery into protective plastic box and set onto a nearby shelf.
    6. Make the low-voltage cable connections between the battery and backup pump.
    7. Plug into a 110-volt electrical outlet the battery charger and the power cord for the 110-volt primary sump pump.
    8. Test the operation of the primary pump by reaching into the sump pit and lifting the flow valve until the pump starts. Repeat to test the battery-powered backup pump.
    • Difficulty: Moderate
      Requires only basic plumbing skills
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      Tools List

      • multi-bit screwdriver
        Screwdriver
      • handsaw
        Handsaw
      • utility knife
        Utility knife

      Shopping List

      110-volt sump pump with battery-powered backup sump pump

      Check valve

      Deep-cycle 12-volt marine battery with protective box

      Teflon tape

      1½-inch-diameter PVC pipe and assorted fittings

      PVC primer and cement

      Stainless steel hose clamps and hose-clamp connector