Replace a pressure switch for a water well by turning off the power, disconnecting the wiring, draining the tank, removing the old switch and installing the new one. All pressure switches eventually require replacement. The job requires no special tools or experience, and most owners can complete it in about an hour. Pressure switches are available at home improvement, plumbing and online stores for about $25 as of 2015.
Locate the circuit breaker that provides power to the well pump, and turn it to the off position. Label each wire that connects to the switch, and disconnect the conduit from the cover. Check the inside of the switch housing for the pressure range of the switch, and replace it with one that has the same range.
Close the valve between the pressure tank and house, and open the drain at the base of the tank to drain the water and relieve the pressure. Unscrew the old switch from the 1/4-inch nipple. This is a good time to replace the nipple and the pressure gauge, components that are often affected by minerals in the water.
Wrap the threads of all pipe connections with Teflon tape. Connect the wires and conduit to the new switch. Open the valve, and turn on the power to the pump.