How to Adjust Your Well Pump Pressure Tank

What you're adjusting and why it matters

Your well pump pressure tank has two separate air pressures inside it, and adjusting them keeps your pump from running constantly or failing to deliver water when you turn on a tap. The tank contains both water and compressed air separated by a rubber bladder. When you adjust pressure, you're setting the air pressure on the empty side of that bladder—not the water pressure itself.

Most residential well systems run between 30 and 50 pounds per square inch (PSI). The pump turns on when pressure drops to the lower setting (usually around 30 PSI) and shuts off when it reaches the upper setting (usually around 50 PSI). If these numbers drift, your pump either cycles on and off too often or doesn't turn on when you need water. Adjusting the air pressure in the tank fixes this without replacing the tank or pump.

Key Takeaways

Well pump pressure tanks have an air valve on top that looks like a car tire valve, and you adjust air pressure there using a tire gauge and air pump.
The air pressure should be set about 2 PSI below your pump's cut-in pressure—usually around 28 PSI if your pump turns on at 30 PSI.
You must turn off the pump and drain the tank completely before adjusting air pressure, or you risk injuring yourself and damaging the tank.
Check air pressure once a year because air naturally leaks out of the tank over time, and low air pressure is the most common reason pumps cycle too frequently.

Gather your tools and safety equipment

You need a tire pressure gauge (the kind used for car or truck tires works fine), an air pump or compressor, and a way to turn off power to the pump. A standard bicycle pump will not deliver enough pressure—you need either a hand pump rated for PSI above 50, or access to an air compressor. Many hardware stores and gas stations have air compressors you can use for free or a small fee.

Wear safety glasses because pressurized air can spray water or debris when you open the valve. Have a bucket or towels nearby in case water drips from the tank. If your pump has a pressure switch (a small box mounted on the pipe near the tank), take a photo of the numbers on it before you start—these tell you what your current cut-in and cut-out pressures are set to.

Turn off the pump and drain the tank

Locate the electrical switch that controls your pump—it is usually mounted on the wall near the tank or on the pump itself. Switch it to the OFF position. If you cannot find a switch, turn off the circuit breaker that powers the pump at your home's electrical panel.

Open the lowest faucet in your house (usually a basement sink or outdoor spigot) and let water run until nothing comes out. This drains the water side of the tank. Wait at least five minutes after the water stops flowing to make sure the tank is fully empty. Do not skip this step—opening the air valve on a pressurized tank can cause serious injury.

Check the current air pressure

Locate the air valve on top of the pressure tank. It looks identical to a car tire valve and usually has a plastic cap you can unscrew by hand. Remove the cap and press your tire gauge onto the valve stem firmly until you hear a small hiss of air. The gauge will show you the current air pressure in PSI.

Write down this number. If the gauge reads zero or very low (below 10 PSI), that is why your pump is cycling too often—air has leaked out over time. If the gauge reads higher than your pump's cut-in pressure (for example, 35 PSI when the pump should turn on at 30 PSI), the tank has too much air and your pump will not turn on at all.

Adjust the air pressure to the correct level

The target air pressure is usually 2 PSI below your pump's cut-in pressure. If your pump turns on at 30 PSI (the most common setting), set the tank air pressure to 28 PSI. If you are unsure of your pump's cut-in pressure, check the pressure switch mounted near the tank—it will have two numbers labeled, usually something like "30/50" (cut-in at 30, cut-out at 50).

If the current air pressure is too low, attach your air pump or compressor to the valve and pump air in slowly until the gauge reads your target pressure. If the current air pressure is too high, press the valve stem with a small screwdriver or the back of your gauge to release air until you reach the target. Work slowly—it is easier to add air than to remove it precisely.

Once you reach the target pressure, remove the gauge and screw the plastic cap back onto the valve. Do not overtighten it.

Turn the pump back on and test

Switch the pump back on at the electrical switch or circuit breaker. Open a faucet and let water run for 30 seconds. The water should flow steadily. Close the faucet and listen—the pump should turn off within a few seconds and stay off while you are not using water.

Open another faucet in a different part of the house and run water again. The pump should turn back on smoothly without stuttering or making grinding noises. If the pump still cycles on and off rapidly, or if water pressure feels weak, the air pressure may need another small adjustment. Turn off the pump again, drain the tank, and recheck the air pressure with your gauge.

Common mistakes and how to avoid them

The biggest mistake is adjusting air pressure while the tank is still full of water. This is dangerous and will not work—you cannot compress air that is already under pressure. Always drain the tank completely and wait several minutes before opening the air valve.

Another common error is setting the air pressure too high. If you pump the tank up to 40 or 50 PSI thinking "more air is better," your pump will never turn on because the air pressure will already exceed the cut-in setting. Remember: the air pressure should be about 2 PSI lower than the pump's cut-in pressure, not equal to it or higher.

Some people adjust the pressure switch itself instead of the tank air pressure. The pressure switch is the small box with two adjustment screws mounted on the pipe near the tank. Unless your pump is not turning on at all, you should adjust the tank air pressure first—that fixes most cycling problems. Only adjust the pressure switch if the tank air pressure is correct and the pump still does not behave properly.

When to check pressure and what to expect

Check your tank air pressure once a year, ideally in the fall before winter stress on the system. Air naturally leaks out of tanks over time—even a well-sealed tank may lose 1 to 2 PSI per month. If you find yourself adjusting pressure more than twice a year, the tank bladder may be failing and the tank may need replacement.

After you adjust pressure, the pump should run less frequently and your water pressure should feel more consistent. If you notice the pump running constantly even after adjustment, or if water pressure drops suddenly, there may be a leak in the water lines or the pump itself may be failing. Those are separate problems that require different repairs.

Frequently Asked Questions

What if I do not know my pump's cut-in pressure?

Look for a small box mounted on the pipe near the tank called a pressure switch. It will have two numbers printed on it or two adjustment screws labeled with numbers. These are your cut-in and cut-out pressures. If you cannot find a label, take a photo and search online for your pump model number, or contact a local well service company—they can tell you the standard settings for your system in one phone call.

Can I use a bicycle pump to adjust the pressure?

No. A bicycle pump does not generate enough pressure to reach the PSI levels needed for a well tank. You need either a hand pump rated for at least 50 PSI, or access to an air compressor at a gas station or hardware store. Trying to use a bicycle pump will waste your time and effort.

What happens if I set the air pressure too high?

If the air pressure exceeds your pump's cut-in pressure, the pump will not turn on even when you use water and the tank pressure drops. You will have no water until you release some air from the tank. This is why it is important to adjust slowly and check the gauge frequently—it is much easier to add air than to remove it precisely.

How often should I check the air pressure?

Check it once a year, usually in the fall. Air leaks out naturally over time, so even a properly adjusted tank will lose some pressure over months. If you find yourself adjusting more than twice a year, the rubber bladder inside the tank may be deteriorating and the tank may need replacement soon.

Do I need to turn off the pump before checking the pressure?

Yes. Always turn off the pump and drain the tank before opening the air valve. If you check pressure while the tank is full and pressurized, you risk injury from pressurized water spray, and you will not get an accurate reading anyway.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.