What a pressure switch does and why testing matters
Your well pump pressure switch turns the pump on when water pressure drops below a set point and turns it off when pressure reaches the upper limit. If the switch fails, your pump either runs constantly (wasting energy and wearing out faster) or stops working altogether, leaving you without water. Testing the switch tells you whether it is responding to pressure changes or stuck in one position.
You can test a pressure switch with basic tools—a pressure gauge and a multimeter—without calling a technician. The test takes about 15 minutes and shows you exactly what the switch is doing. If it fails the test, you know the switch needs replacement rather than spending time troubleshooting the pump itself.
Key Takeaways
- A pressure switch that does not respond to pressure changes will cause your pump to run nonstop or not run at all.
- You can test the switch using a pressure gauge attached to the tank and a multimeter to check electrical continuity.
- The switch should close (allow current to flow) when pressure drops and open (stop current) when pressure rises above the cut-off point.
- Most residential switches are set to cut in around 30 psi and cut out around 50 psi, though your system may differ.
- If the switch fails either test, replacement is the only fix—switches cannot be repaired.
Gather your tools and locate the switch
You will need a pressure gauge (a straightforward dial gauge costs $15–30 and screws onto the tank's gauge port), a multimeter set to measure continuity or resistance (around $20–40 for a basic model), and a flathead screwdriver to open the switch cover. Have a bucket or towel nearby in case water drips when you remove the gauge.
The pressure switch is a small cylindrical or box-shaped device mounted on top of or near the pressure tank, usually with two wires running to it. Before you start, turn off power to the pump at the breaker. This is essential—you are working with electrical connections, and the pump should not start while you are testing.
Locate the gauge port on the tank (a small threaded opening, often with a plastic cap). Screw the pressure gauge onto this port by hand until it is snug. Do not use a wrench—hand-tight is enough. The gauge will show you the current tank pressure and let you watch it change as you run the test.
Test the switch for electrical continuity
Set your multimeter to the continuity or resistance setting (the symbol looks like a sound wave or ohm sign, depending on your meter). Continuity mode beeps when electricity can flow through a connection; resistance mode shows a number close to zero for a good connection.
With the pump power still off, touch one multimeter probe to each of the two wires connected to the switch. If the switch is in the "on" position (pump should be running), the meter should show continuity or very low resistance (usually under 5 ohms). If the meter shows no continuity or very high resistance, the switch contacts are stuck open and the switch has failed.
Now turn the pump power back on and let it run until the pressure gauge reads the upper cut-off point (usually 50 psi, but check your switch label). Once the pump shuts off, test the switch again with the multimeter. This time it should show no continuity or very high resistance, meaning the contacts have opened and stopped sending power to the pump. If it still shows continuity, the switch is stuck closed and cannot turn the pump off.
Manually drain the tank to test the cut-in point
The cut-in point is the pressure at which the switch turns the pump back on. To test it, you need to lower the tank pressure below the cut-in setting. Turn off the pump power again. Open a faucet inside the house and let water run until the pressure gauge drops to around 20 psi, then close the faucet.
With the pump still off, test the switch with the multimeter again. At this low pressure, the switch should show continuity (contacts closed, ready to send power). If it does not, the switch is stuck open and will not restart the pump when pressure drops.
Now turn the pump power back on. The pump should start when ready because pressure is below the cut-in point. Watch the gauge rise. The pump should shut off when pressure reaches the upper limit (usually 50 psi). Test the switch one more time with the multimeter—it should show no continuity, confirming the contacts opened.
What the test results mean
If the switch showed continuity at low pressure and no continuity at high pressure, and the pump turned on and off at the right times, the switch is working correctly. You can turn the power back on, remove the pressure gauge, and cap the gauge port.
If the switch showed continuity at both high and low pressure, it is stuck closed and will not turn the pump off. The pump will run continuously, the pressure will climb past the normal cut-off point, and you may hear the pump strain or see the pressure relief valve open. This switch must be replaced.
If the switch showed no continuity at low pressure, it is stuck open and will not turn the pump on when pressure drops. You will have no water pressure until the switch is replaced. If the switch showed continuity at high pressure, it will not turn the pump off, leading to the same continuous-run problem as a stuck-closed switch.
In all failure cases, the switch itself is faulty. Switches are sealed units and cannot be repaired—replacement is the only option. A new pressure switch costs $50–150 depending on the model, plus labor if you hire a technician to install it.
Common mistakes that lead to wrong test results
The most common error is testing the switch while the pump is running. You must turn off power before touching the wires with the multimeter. Testing a live circuit can damage the meter and create a shock hazard.
Another mistake is not waiting for the pressure to stabilize before testing. After you turn the pump on or off, wait 10–15 seconds for the pressure gauge to settle on a steady reading before checking the switch with the multimeter. Pressure bounces slightly as the pump starts or stops, and testing during that bounce can give a false reading.
Some people test the switch without a pressure gauge and assume the pump is at the right pressure. Without the gauge, you cannot confirm what pressure the switch is actually responding to. The gauge is cheap and essential—do not skip it.
Finally, do not assume a switch has failed just because the pump runs longer than you expect. Pump runtime depends on how much water was used since the last cycle. If someone took a long shower, the pump will run longer to refill the tank. A switch that turns on and off at consistent pressure points is working correctly, even if the timing varies.
When to call a professional instead
If you are not comfortable working with electrical connections or the multimeter readings are unclear, a well technician can run this test in minutes. They can also check whether the pressure tank itself is losing air (a common cause of frequent pump cycling that looks like a switch problem) and confirm the cut-in and cut-out pressures are set correctly for your system.
If the switch passes all tests but the pump still runs constantly or will not start, the problem is elsewhere—in the pump itself, the check valve, or the tank. A technician can narrow down the cause and recommend the next step.
Frequently Asked Questions
What if my pressure gauge shows the pump is running but the pressure is not rising?
The pump may be running but not building pressure, which usually means water is leaking out of the tank or the check valve is stuck open. This is not a switch problem. Turn off the pump and check for leaks around the tank and pipes. If you find none, the check valve or pump itself may have failed.
Can I test the switch without turning off the power?
No. Testing the switch while power is on creates a shock hazard and can damage the multimeter. Always turn off power at the breaker before touching the wires. The test takes a few minutes longer, but safety comes first.
What pressure should my switch cut in and cut out at?
Most residential switches are set to cut in around 30 psi and cut out around 50 psi. Check the label on your switch—it will show the exact settings for your model. If you do not see a label, a technician can tell you the correct settings for your system.
If the switch fails the test, can I adjust it instead of replacing it?
Some switches have an adjustment screw, but if the switch is stuck open or closed, adjusting it will not help. The internal contacts are faulty and cannot be fixed. Replacement is the only solution. If the switch is working but the cut-in or cut-out pressure is wrong, a technician can adjust it, but that is different from a failed switch.
How often should I test my pressure switch?
Test the switch if the pump is running constantly, will not start, or cycles on and off more often than usual. You do not need to test it during routine maintenance unless you suspect a problem. Most switches last 5–10 years before failing.