Where the pressure adjustment lives on a well system

The pressure switch and pressure tank control how hard water flows from your taps. On most residential well systems, the pressure switch is a small box mounted on the pipe that runs from the tank to your house — usually in the basement, pump house, or utility room. The switch sits between the tank and the check valve, and it tells the pump when to turn on and off based on the pressure inside the tank.

Before you touch anything, turn off power to the pump at the breaker. The pressure switch has two adjustment screws on top: a larger one (usually with a nut around it) that sets the cut-off pressure — when the pump stops — and a smaller one that sets the cut-in pressure, or the point where the pump starts again. The difference between these two is called the differential, and it is usually set to 20 pounds per square inch (psi).

Key Takeaways

  • The pressure switch controls when your pump turns on and off, and it sits on the main pipe between your pressure tank and house.
  • The larger adjustment screw raises or lowers the cut-off pressure (when the pump stops), and turning it clockwise increases pressure.
  • You need a pressure gauge to see what pressure you are actually working with — guessing will waste time and risk damaging the tank.
  • Most household well systems run between 40 and 60 psi, with 50 psi a common middle ground for normal use.
  • After any adjustment, run water from a tap for a few minutes to let the system stabilize before reading the gauge again.

How to read your current pressure and set your target

Screw a pressure gauge onto the test port on top of the pressure tank — it looks like a tire valve. If there is no test port, you can install one, but for now assume your tank has one. Turn on a tap and let water run until the pump kicks in, then turn the tap off and watch the gauge. The pressure will climb as the pump runs. When the pump shuts off, that number is your cut-off pressure. Write it down.

Now turn on another tap and let water drain from the tank. The pressure will drop. When the pump turns back on, that is your cut-in pressure. The gap between the two is your differential. Most systems are set to cut in at 40 psi and cut off at 60 psi, giving a 20 psi swing. If your water pressure feels weak at the tap, you may need to raise both numbers. If the pump is cycling on and off too often, you may need to lower them or check whether your tank is waterlogged.

Adjusting the cut-off pressure (the main screw)

The larger screw with a nut around it controls the cut-off pressure — the point where the pump stops. Turning it clockwise (to the right) raises the pressure; turning it counterclockwise (to the left) lowers it. Make small turns: a quarter turn usually changes the pressure by 2 to 3 psi. After each adjustment, turn the power back on and let the pump run until it shuts off, then check your gauge again.

If you want stronger water pressure throughout the house, raise the cut-off pressure by turning the screw clockwise. If the pump is running too often or too hard, lower it by turning counterclockwise. Most household systems work well between 50 and 60 psi at cut-off. Going above 60 psi puts extra strain on pipes and fixtures and can shorten the life of your tank. Going below 40 psi usually means weak flow at the tap, especially if you are running multiple fixtures at once.

Adjusting the cut-in pressure (the smaller screw)

The smaller screw controls the cut-in pressure — when the pump starts. It works the same way: clockwise raises it, counterclockwise lowers it. However, you almost never need to touch this screw. The differential (the gap between cut-in and cut-off) should stay at 20 psi for most systems. If you raise the cut-off pressure, the cut-in pressure will usually follow automatically because the switch is designed to maintain that gap.

The only reason to adjust the cut-in screw separately is if you want to change the differential itself — for example, if your pump is cycling too frequently, a wider differential (25 or 30 psi instead of 20) can help. But this is rare and usually a sign that your tank is losing its air charge or that you have a leak somewhere. Before you adjust the cut-in screw, check whether your tank needs air added to it.

Checking and adding air to the pressure tank

A pressure tank has two chambers: one holds water, and one holds compressed air. Over time, the air charge leaks out, and the tank becomes waterlogged. When this happens, the pump cycles on and off constantly, even if the pressure settings are correct. You can check the air charge by turning off the pump and draining the tank completely, then listening near the air valve (a small tire-like valve on top of the tank) for a hiss of air escaping. If you hear nothing, the tank is likely waterlogged.

To add air, turn off the pump and drain the tank by opening a low tap until no water comes out. Then use an air compressor to add air through the air valve until the gauge reads about 2 psi below your cut-in pressure. For a system that cuts in at 40 psi, you would add air until the gauge reads 38 psi. This gives the water room to expand as pressure builds. If you do not have an air compressor, a bicycle pump works but takes longer. After adding air, close the valve, turn the pump back on, and check your pressure gauge again.

What to do if pressure keeps dropping or the pump will not stop

If you adjust the pressure switch and the pressure still drops quickly, or if the pump runs constantly, you likely have a leak in the system or a failing tank. A leak can be in the house plumbing, the pressure tank itself, or the check valve. To find out, turn off the pump and watch the gauge. If the pressure drops while the pump is off, you have a leak. If the pressure holds steady, the pump itself may be failing.

A waterlogged tank will also cause the pump to run constantly. If you added air and the problem persists, the tank's internal bladder (the rubber chamber that holds the air) may have ruptured. Tanks usually last 10 to 15 years before the bladder fails. If you suspect a leak or a failing tank, you will need to call a well contractor to inspect the system. These are not adjustments you can make yourself.

Safety steps before and after adjustment

Always turn off power to the pump at the breaker before you open the pressure switch or work on the tank. Even though the switch itself is not powered, the pump can start unexpectedly if you do not. Leave the power off while you are adjusting the screws. After you make an adjustment, turn the power back on and let the system run for at least five minutes before you check the gauge. The pressure needs time to stabilize.

Do not adjust the pressure above 80 psi. Most residential tanks are rated for 100 psi maximum, but pressures above 80 psi can damage water heaters, washing machines, and other fixtures. If you need pressure higher than 60 psi to get adequate flow, the problem is usually not the switch — it is a leak, a waterlogged tank, or a pump that is too small for your household demand. A well contractor can help you figure out which.

Frequently Asked Questions

What pressure should I set my well system to?

Most household systems work well at 40 to 60 psi, with 50 psi a common target. If you want stronger flow at the tap, raise the cut-off pressure to 55 or 60 psi. If the pump is cycling too often, lower it to 45 or 50 psi. Check your water heater and washing machine manuals — some have maximum pressure limits of 80 psi.

How often should I adjust the pressure switch?

You should not need to adjust it more than once or twice a year. If you are adjusting it monthly, you likely have a leak, a waterlogged tank, or a pump that is undersized. These are problems that need diagnosis, not repeated tweaking of the switch.

Can I adjust the pressure switch myself, or do I need a contractor?

You can adjust the two screws yourself if you have a pressure gauge and follow the steps carefully. However, if the pressure will not hold steady, if the pump will not stop running, or if you are not comfortable working with the system, call a well contractor. Mistakes can damage the tank or pump.

What does it mean if the pump runs constantly even after I adjust the pressure?

Constant running usually means a leak in the house plumbing, a failing check valve, or a waterlogged pressure tank. Turn off the pump and watch the gauge for five minutes. If the pressure drops, you have a leak. If it holds steady, the tank or pump may be failing and needs professional inspection.

How do I know if my pressure tank needs air added?

Drain the tank completely and listen at the air valve on top. If you hear air hiss out, the tank has an air charge. If you hear nothing, it is waterlogged. You can also watch how often the pump cycles — a waterlogged tank causes the pump to turn on and off much more frequently than normal.