Pressure Switch — Well System Glossary
A pressure switch monitors water pressure in the system and signals the well pump to turn on when pressure drops below the cut-in setting and off when it reaches the cut-out setting.
The pressure switch is the component that tells your well pump when to turn on and when to turn off. It monitors water system pressure continuously and activates the pump when pressure drops to the cut-in threshold, then shuts it off when pressure reaches the cut-out setting.
How a Pressure Switch Works
The pressure switch is typically a small electrical box mounted on the pipe near the pressure tank. Inside, a spring-loaded diaphragm responds to changes in water pressure. When pressure falls to the cut-in setting (commonly 30 PSI or 40 PSI), the diaphragm movement closes the electrical contacts and sends power to the pump motor. When pressure builds to the cut-out setting (50 PSI or 60 PSI), the contacts open and the pump stops.
The difference between cut-in and cut-out is called the pressure differential, typically 20 PSI. This range is what your pressure tank is designed to operate within. The tank's air precharge is set 2 PSI below the cut-in pressure so the bladder can properly buffer water delivery across the full pressure range.
Common Pressure Switch Settings
Residential well systems use either 30/50 PSI or 40/60 PSI settings. The 30/50 setting is more common in older systems and single-story homes. The 40/60 setting provides more consistent pressure for multi-story homes or higher-demand households. Either setting works as long as the pressure tank's precharge is correctly calibrated to match.
Signs of Pressure Switch Problems
A failing pressure switch can present in several ways: the pump not starting when water demand drops pressure below the cut-in point, the pump running continuously without shutting off, incorrect pressure readings that cause the pump to cycle at the wrong thresholds, or visible corrosion or pitting on the switch contacts that prevents reliable operation.
Importantly, rapid clicking from the pressure switch area is often misdiagnosed as a switch failure. More commonly, this clicking indicates a waterlogged pressure tank — the pump is short cycling because the tank has lost its air cushion, and the switch is simply responding to the rapid pressure drops. Always check the pressure tank before replacing a pressure switch.
Replacement Cost and Considerations
Pressure switch replacement is one of the less expensive well system repairs, typically $150 to $300 including parts and labor. The switch itself usually costs $15 to $50. However, a pressure switch replacement should be paired with a pressure tank inspection — if the switch was struggling because of a waterlogged tank, replacing only the switch will not resolve the underlying problem.