When and why to replace your pressure tank

A water pressure tank fails when the internal bladder ruptures, the air charge leaks out, or corrosion eats through the steel shell. When this happens, your pump cycles on and off constantly, your water pressure swings wildly, or you lose pressure altogether. Replacement is the only real fix—repair kits exist but rarely work on tanks more than 10 years old.

Most residential tanks last 5 to 15 years depending on water quality and how hard your pump works. If your tank is making noise, leaking from the seams, or your pressure gauge swings between 20 and 80 psi instead of staying steady, the tank itself is probably dead. Before you replace it, confirm the tank is the problem: check that your pressure switch is working and your pump isn't stuck in a cycle. If the pump runs constantly and pressure won't build, the tank is almost certainly your culprit.

Key Takeaways

  • A failed pressure tank causes your pump to cycle constantly or pressure to swing wildly, and replacement is usually the only solution.
  • You will need to shut off power to the pump, drain the system, and disconnect the tank from the plumbing and electrical lines before removal.
  • The new tank must match your system's pressure rating and be sized for your household's water use—undersizing causes the pump to run too often.
  • Filling the air charge in the new tank requires a bicycle pump or air compressor and must be done before you reconnect the plumbing.
  • This is a job you can do yourself if you are comfortable with basic plumbing, but hiring a plumber is reasonable if you are unsure about pressure settings or air charge.

Choosing the right replacement tank

Tank size matters more than most homeowners realize. A tank that is too small forces your pump to turn on and off constantly, wearing it out faster and wasting energy. A tank that is too large takes up space and costs more. For a typical household of three to four people with a 0.5 to 1 horsepower pump, a 20 or 30-gallon tank is standard. If you have high water demand—multiple bathrooms, a lawn irrigation system, or a large garden—a 40 or 50-gallon tank may be worth the extra cost.

Check the nameplate on your old tank or pump to find the pressure rating, usually 30/50 psi or 40/60 psi. This tells you the pressure range your system is designed for. Buy a replacement tank with the same rating. The tank itself will have a label showing its maximum working pressure—make sure it matches or exceeds your system's rating. Steel tanks are standard and affordable; stainless steel costs more but resists corrosion if you have acidic or high-mineral water.

Shutting down and draining the system

Turn off power to the pump at the breaker or switch. If your pump is wired directly to the breaker, flip the breaker to the off position. Wait a few minutes to let any residual pressure bleed away, then open a faucet somewhere in the house to confirm the pump is not running.

Locate the drain valve at the lowest point of your plumbing system—usually near the pressure tank or at the well head. Attach a garden hose to the drain valve and run it outside or to a floor drain. Open the valve slowly and let the system drain completely. This may take 10 to 20 minutes depending on how much water is in your pipes. Once water stops flowing, close the drain valve.

Removing the old tank

The pressure tank connects to your plumbing system through a fitting called a tee or union at the top. You will see the pump line coming in, a pressure gauge, a pressure switch, and a drain valve. Before you disconnect anything, take a photo of the connections so you remember how they go back together.

Use two wrenches—one to hold the fitting steady and one to turn the nut—to disconnect the union or fitting. Work slowly to avoid stripping the threads. Once the plumbing is loose, disconnect the pressure switch by unplugging the wire connector or unscrewing the terminal screws. If the tank is bolted to a stand or wall, remove those bolts. Drain any remaining water from the tank by opening the drain valve again, then carefully tip or roll the tank away from the wall. Old tanks are heavy—a 30-gallon tank weighs about 60 pounds when empty—so get help if you need it.

Installing the new tank and charging the air bladder

Before you connect the new tank to your plumbing, you must charge the air bladder inside it. Every pressure tank has a small air valve at the top, similar to a tire valve on a car. The air inside the bladder cushions the water and helps maintain steady pressure. New tanks come partially charged from the factory, but you need to check and adjust the charge to match your system.

Use a bicycle pump or air compressor with a pressure gauge to check the air charge. The correct pressure is usually 2 psi below your pump's cut-in pressure—so for a 30/50 system, you want about 28 psi in the tank. Unscrew the plastic cap on the air valve and attach your pump or gauge. If the pressure is low, add air until you reach the target. If the pressure is too high, press the valve stem to release air. Once the charge is correct, replace the cap and move the tank into position.

Reconnect the plumbing using two wrenches to tighten the union or fitting. Do not over-tighten—hand-tight plus a quarter turn is usually enough. Reconnect the pressure switch by screwing the terminal screws back in or plugging in the wire connector. If your old tank had a pressure gauge, unscrew it from the old tank and screw it onto the new one in the same location.

Refilling and testing the system

Close the drain valve if it is still open. Turn the pump back on at the breaker. You should hear the pump start and run for a minute or two as it fills the tank and builds pressure. Watch the pressure gauge—it should climb steadily from zero to your cut-out pressure (usually 50 or 60 psi) and then stop. If the pump keeps running past that point, the air charge in the tank is too low and you need to add more air.

Once the pump stops, open a faucet inside the house and let water run for a few seconds. The pressure should stay steady. Close the faucet and the pump should not turn back on when ready—if it does, the tank is undersized or the air charge is still wrong. Turn the pump off, drain the system again, and recheck the air pressure in the tank. Once everything is working smoothly, turn the pump back on and monitor it for the next few hours to make sure the pressure stays stable and the pump is not cycling constantly.

When to call a plumber

If you are not comfortable working with pressurized plumbing systems, or if you are unsure about the correct air charge for your tank, hiring a plumber is the safer choice. A plumber can also help if your old tank was a different size than what you are installing, because that may require adjusting your pressure switch settings. If your pump does not stop running after you install the new tank, or if pressure swings wildly, a plumber can diagnose whether the problem is the tank, the switch, or the pump itself.

Expect to pay a plumber $300 to $600 for tank replacement, including labor and the tank itself. If you buy the tank yourself and have the plumber install it, the cost is usually lower. Get a quote before work begins.

Frequently Asked Questions

How do I know if my pressure tank is bad or if the problem is something else?

A bad tank usually causes the pump to run constantly or pressure to swing between very high and very low. If the pump runs for a few minutes and then stops, and pressure stays steady, the tank is probably fine. You can also tap the tank with a wrench—a hollow sound means it is full of water and the bladder has failed. A dull thud means the air charge is still there.

Can I use a larger tank than my system was designed for?

Yes, a larger tank is fine and often better—it gives your pump longer rest periods and reduces wear. The only downside is cost and space. A smaller tank than recommended will cause your pump to cycle too often and wear out faster, so avoid going smaller.

What pressure should I charge the air bladder to?

The correct charge is 2 psi below your pump's cut-in pressure. For a 30/50 system, charge to 28 psi. For a 40/60 system, charge to 38 psi. Check the nameplate on your pump or pressure switch to find your system's pressure range.

Do I need to replace the pressure switch when I replace the tank?

Not usually. The pressure switch controls when the pump turns on and off, and it is separate from the tank. If the switch is working correctly, you can reuse it. If the pump does not stop running after you install the new tank, the switch may be stuck and need replacement.

How long does a new pressure tank last?

Most tanks last 5 to 15 years. Steel tanks in areas with soft water tend to last longer. Hard water or acidic water can shorten the life. Stainless steel tanks resist corrosion better but cost more upfront. Proper air charge and regular maintenance help extend the tank's life.