Why and when to drain your pressure tank

A pressure tank holds water under pressure so your well pump doesn't run constantly every time you turn on a faucet. Over time, air gets absorbed into the water inside the tank, and the cushion of compressed air that keeps pressure steady shrinks. When this happens, your pump cycles on and off more often than it should, wears out faster, and your water pressure becomes uneven. Draining the tank resets the air charge and restores normal operation.

You'll know it's time to drain when your pump starts running in short bursts even when you're not using much water, or when you notice pressure dropping suddenly after you use water. Most homeowners drain their tank once every one to three years, depending on water quality and how hard the pump works.

The job takes about 30 minutes and requires no special tools beyond what you likely have in a toolbox. You do not need to call a professional for this maintenance task, though if your tank is leaking, rusted, or more than 15 years old, a plumber should inspect it.

Key Takeaways

  • Draining a pressure tank resets the air charge inside and stops your pump from cycling too often.
  • Turn off the pump at the breaker, open a faucet to release pressure, and drain the tank through the drain valve at the bottom.
  • The whole process takes 20 to 30 minutes and requires only a bucket and possibly a wrench.
  • After draining, close the drain valve, turn the pump back on, and let it refill and pressurize before using water normally.
  • If water sprays from the air valve or the tank is visibly corroded, have a plumber inspect it before continuing.

Turn off the pump and release system pressure

Start by switching off the pump at your home's electrical breaker. This prevents the pump from running while the tank is empty and protects the pump from damage. If you're not certain which breaker controls the well pump, look for one labeled "well" or "pump," or trace the power line from the pump to the panel.

Next, open any faucet in your home—a kitchen sink or bathroom tap works fine—and let water run until it stops flowing. This releases the pressure built up in the tank and pipes. You should hear air hissing out as pressure drops. Once the water stops, close the faucet.

Wait a few minutes before moving to the next step. This gives any remaining pressure time to equalize throughout the system.

Locate and open the drain valve

The drain valve is a small brass or plastic fitting at the bottom of the pressure tank. It looks like a garden hose spigot or a small lever handle. If your tank is in a basement or utility room, position a bucket underneath the valve to catch water. If the tank is outside or near a floor drain, you may not need a bucket, but have one ready just in case.

Turn the valve counterclockwise by hand if it has a handle, or use an adjustable wrench if it's a hex-head fitting. Open it slowly at first—water may spray out if pressure hasn't fully released. Once the valve is open, let all the water drain from the tank. This usually takes 5 to 10 minutes. You'll know the tank is empty when water stops dripping from the valve.

Leave the drain valve open while the tank sits empty. This allows air to enter and prevents a vacuum from forming inside.

Check the air valve while the tank is empty

At the top of the pressure tank, you'll see a small air valve that looks like a tire valve on a car. This is where the air charge lives. While the tank is drained and depressurized, this is a good time to inspect it.

Press the valve stem gently with your finger. A small amount of air should hiss out—this is normal. If water sprays out instead, the internal bladder or diaphragm inside the tank has failed, and the tank needs to be replaced. Do not proceed with refilling; contact a plumber to replace the tank.

If only air comes out, the valve is working correctly. You can now close the drain valve and prepare to refill.

Close the drain valve and refill the tank

Turn the drain valve clockwise by hand or wrench until it's snug. Do not over-tighten—hand-tight is sufficient. If the valve leaks after you close it, tighten it slightly more, but stop if you feel strong resistance.

Now turn the pump back on at the breaker. The pump will start and begin filling the tank with water. You'll hear the pump running and water flowing through the pipes. Let the pump run until it shuts off on its own—this usually takes 2 to 5 minutes, depending on tank size and water pressure. The pump stops when the tank reaches its maximum pressure setting, which is typically 60 pounds per square inch (psi) on most residential systems.

Once the pump shuts off, open a faucet briefly to confirm water is flowing normally and pressure feels steady. Close the faucet and wait a minute. If the pump runs again in a short burst and then stops, this is normal—it's just topping off pressure. Your tank is now reset.

Signs your tank needs professional attention

If water sprayed from the air valve during inspection, the tank's internal bladder has failed and must be replaced. This is not a repair you can do yourself—contact a plumber with well system experience.

If the tank is visibly rusted, dented, or leaking from seams, it has reached the end of its life. Rust weakens the metal and can eventually cause the tank to fail suddenly. A plumber can assess whether repair or replacement is needed.

If the pump continues to cycle on and off in short bursts even after you've drained the tank, the problem may be a faulty pressure switch or a leak in the system rather than a depleted air charge. A plumber can diagnose this with a pressure gauge.

How often to drain and what to expect long-term

Most well systems benefit from draining once per year or every 18 months. If your water is high in minerals or sediment, you may need to drain more often—every 6 to 12 months. If your water is very clean and your pump doesn't run heavily, you might stretch it to every two or three years.

Mark your calendar after you drain so you remember when to do it next. Some homeowners set a phone reminder for the same month each year. Over time, you'll notice whether your pump cycles more or less frequently, which tells you whether your interval is right.

Draining your tank regularly adds years to your pump's life because the pump doesn't have to work as hard to maintain pressure. It's one of the simplest maintenance tasks you can do on a well system, and it costs nothing but a few minutes of your time.

Frequently Asked Questions

Can I drain the tank while the pump is running?

No. Always turn off the pump at the breaker first. If the pump runs while the tank is empty, it can overheat and burn out. Turning off the pump takes two seconds and protects a piece of equipment that costs hundreds of dollars to replace.

What if the drain valve is stuck and won't turn?

explore penetrating oil like WD-40 around the valve stem and wait 15 minutes. Then try again with a wrench, turning slowly and steadily. If it still won't budge, stop—forcing it can break the valve. Call a plumber; they have tools to remove stuck valves without damaging the tank.

How do I know if my tank's air pressure is correct?

You need a tire pressure gauge to check the air valve at the top of the tank. The correct pressure is usually 2 psi below your pump's cut-in pressure—typically 38 psi on a system set to cut in at 40 psi. Your pump's pressure switch should have this information labeled on it. If you're unsure, a plumber can set it for you.

Is it normal for the pump to run briefly after I turn it back on?

Yes. After draining and refilling, the pump will run until it reaches the tank's maximum pressure setting. Once it shuts off, it may run again in short bursts over the next hour as the system settles. This is normal and not a sign of a problem.

What should I do with the water I drained from the tank?

If your well water is clean and you drained it into a bucket, you can use it to water plants or pour it down a drain. If the water looks cloudy or discolored, it's better to dispose of it down a floor drain or outside away from your foundation. Discolored water usually means sediment has settled in the tank, which is another sign draining was needed.