Water Pump Pressure Switch Troubleshooting

Every well system needs a pump to retrieve water from under the ground. To avoid the need for that pump to run whenever water is needed, the system usually includes a tank that stores pressurized water. The pump that pressurizes the water is controlled by a switch that monitors the water pressure, and when the pump starts behaving erratically, this switch may be responsible. It's mounted next to the pressure pump and connected to an electrical cable that comes from the main panel.

The Switch Optimizes Pump Use

When the pressure switch is operating correctly, the pump comes on whenever the water pressure falls below its cut-in value, and it goes off when the pressure rises to its cut-out value. The cut-in and cut-out pressures are determined by the switch, which is often preset -- a typical cut-in setting is 30 pounds per square inch, and a typical cut-out setting is 50 psi. Although the range between cut-in and cut-out values is adjustable, it's usually 20 psi -- this ensures that the pump doesn't have to cycle on too frequently and that it doesn't have to run for too long when it does come on.

Symptoms of Switch Failure

A loss of water pressure in the building serviced by the pump is one sign of a switch failure -- it may have simply failed to tell the pump to come on. Another symptom of a switch malfunction is failure of the pump to switch off, which could over-pressurize the system. Both symptoms can have other causes, such as a leak, an undercharged or waterlogged pressure tank or problems with the well itself. A simple procedure can help determine whether the switch is responsible.

Step 1 Check the Power

If the switch fails to turn off the pump, it may not have power. Check the breaker in the main panel and reset it if it has tripped. Put on a rubber glove and wiggle the wire connected the the switch. The vibrations of the pump can sometimes loosen the switch connections. if the connections are loose, call a plumber or electrician.

Step 2 Double-Check the Pressure

If the pressure gauge mounted on the pump shows that the pressure has fallen below the cut-in value, and the pump isn't responding, try tapping the gauge. The needle may be stuck. If you suspect that the gauge is faulty, double-check it by screwing another gauge into a nearby faucet and opening the faucet all the way.

Step 3 Clean the Terminals

If the power is on, the pump doesn't come on and the pressure falls, the problem can sometimes be traced to debris on the switch terminals. You can check this yourself, but before removing the switch cover, turn off the breaker controlling the pump. Loosen the screw holding the cover, lift the cover off and look at the terminals. If you see debris, such as cobwebs or mouse droppings, brush it off with a 1-inch paintbrush. If the terminals are corroded or damaged, call an electrician.