New foot valve, still losing prime: how to track down air leaks on a shallow-well jet pump

A shallow-well jet pump pulls water up by suction, so the pipe from the well has to hold a solid column of water. Berkeley's owner's manual for its shallow-well jet systems says every suction joint must be airtight as well as watertight, because a pipe that can draw air will not let the pump pull from the well. For a system already in service, the manual's chart lists two reasons a pump loses prime: air leaks on the suction line or shaft seal, and a water level that has fallen below the suction inlet.

Start with the fittings. Berkeley calls for as few fittings as possible, especially elbows, PTFE tape on threaded joints and a pipe that rises slightly from well to pump, since high spots trap air and can stall the pump with an air lock. It says to brush suction connections with soapy water; shaving cream also works. Air spurting from faucets, per the same chart, means a suction-side leak, a gassy well or a pump drawing the well below the foot valve.

To separate a leaking valve from a leaking pipe, Ken's Distributing, a pump-parts supplier, suggests an overnight test: fill the pump, turn it off and look again the next morning. A pump that has lost its prime by then, with nothing dripping above ground, has a valve that isn't sealing. Listening at the wellhead right after shutdown for water draining back gives the same answer sooner. Repeated dry starts also wear out the shaft seal, Ken's warns.

Then check the water and the tank. Berkeley says a well more than 25 feet to water needs a deep-well jet, and it sets the foot valve 5 feet above the well bottom and no less than 10 feet under the water line while the pump runs. If the pump cycles too often, the chart points to a waterlogged tank or low air charge: with power off and pressure released, the precharge should be 2 psi below the switch cut-in, or 28 psi on a 30/50 switch.