Well Pump Pressure Switches
A well pump pressure switch is the small gray box near your pressure tank that turns the pump on when water pressure drops and off when it climbs back up. If your well suddenly gives you no water, weak water or a pump that won't stop, this switch is one of the first things to check.
How the switch works
Every pressure switch has two set points. The cut-in is the pressure where the pump turns on as you use water, and the cut-out is where it shuts off as the tank refills. The gap between them is the differential, so a switch set at 40 psi cut-in and 60 psi cut-out has a 20 psi differential. Inside, a diaphragm fed by a short pipe nipple pushes against springs, and the springs open and close the contacts.
Switches are sold by their range. Boshart's medium duty line, for example, comes in 30-50, 40-60, 50-70 and 60-80 psi models. Some switches add a lever on the side. On a Square D switch the M4 option is a low-pressure cutoff that shuts the pump off when pressure falls 10 psi below the cut-in, and the M1 option is a plain manual off lever.
The problems people hit most
- Pump won't turn on. Often the little pipe feeding the switch is clogged with sediment, iron or rust, or the switch linkage is worn out.
- Pump won't shut off. Contacts stuck closed, or a pump that can no longer reach the cut-out pressure.
- Switch clicks on and off fast. That's usually a waterlogged pressure tank, not the switch.
- Lever switch tripped and no water. The low-pressure cutoff did its job. Something made the pressure drop first.
Our pressure switch problems page walks through each one in order.
Fix, adjust or replace
Start with the job you need:
- Change when the pump starts and stops: how to adjust a well pump pressure switch.
- Get a tripped lever switch running again: low-pressure cutoff switch reset.
- Swap a burned or stuck switch: how to replace a well pressure switch.
A new switch is cheap compared with most well repairs. HomeGuide puts a pressure switch replacement at $150 to $200 with parts and labor.
The switch and the tank work as a pair
The switch only reads the pressure. The pressure tank stores the water and sets how long the pump runs each cycle. If the tank's air charge is wrong, a perfectly good switch will cycle the pump too often, so check the tank before you blame the switch. For pump-side problems, head to our well pump guides.
FAQ
How do I know if my well pump pressure switch is bad?
Signs include a pump that won't start even though the pressure is low, a pump that won't shut off, contacts that are burned or chattering, and a switch that only works after you tap it. Tapping sometimes frees a clogged inlet for a moment. Check the pressure tank and the inlet nipple before you replace the switch.
Do I need a 30/50 or 40/60 pressure switch?
Either works in most houses. The higher setting gives stronger pressure at the tap, but the pump has to be able to reach the higher cut-out. Match the tank's air charge to whichever cut-in you choose.
How much does it cost to replace a well pump pressure switch?
HomeGuide's figure is $150 to $200 installed. The switch itself is a modest part of that, and many homeowners comfortable with basic wiring do it themselves.
How do I reset my well pressure switch?
Only switches with a low-pressure cutoff lever have a reset. You hold the lever at Start until pressure builds, then let go. A switch without a lever has nothing to reset, so if the pump won't run, look for a tripped breaker, a clogged inlet or a failed switch.
All guides in this section
Sources
- Boshart IndustriesHow do I adjust the CUT-IN and CUT-OUT settings of a pressure switch? (opens in a new tab)
- Boshart IndustriesPS02MD Medium Duty Pressure Switches (opens in a new tab)
- Schneider Electric9013: What is the difference between M1 and M4 options? (opens in a new tab)
- HomeGuideHow Much Does Well Pump Repair Cost? (opens in a new tab)
- Boshart IndustriesWhy won't my pressure switch turn on? (opens in a new tab)