A well pressure tank holds water under pressure so the pump does not have to start every time someone opens a tap. When it fails, the house may lose steady pressure, the pump may cycle too often, or the tank may feel waterlogged. This explainer follows a typical replacement from the first shutoff to the final check. Electrical and pump work carries real risk, so if any step is beyond your comfort or training, bring in a licensed well contractor.
Before you touch anything
Confirm the new tank matches the old one in size, connection type, and pressure rating. Check the old tank's label for its rated pressure and its tank size. Gather a pressure gauge, a drain hose, the right fittings, and a way to shut off power to the pump at the breaker. Make sure you know where the pump's power and the well's shutoff are located before the job starts.
Cut power and relieve the system
Turn off power to the pump at the breaker and label the breaker so no one switches it back on during the job. Close the valve between the tank and the house, then open a faucet on the lowest floor to bleed pressure off the lines. Attach a drain hose to the tank drain and let the tank empty. Do not disconnect the tank while it still holds pressure.
Check the old tank's air charge
With the tank empty of water, read the air pressure at the tank's air valve using your gauge. Note the reading. This tells you how the old tank was set and helps you understand whether the failure was air loss or a ruptured bladder. Record the reading in writing so the new tank can be set correctly.
Install and set the new tank
Mount the new tank securely and connect it to the plumbing with the correct fittings. Set the air charge on the new tank to the value the manufacturer specifies for your pump's cut-in pressure, with the tank empty of water. Do not guess this number. Reconnect the tank to the system, open the isolation valve slowly, and bleed any trapped air from the faucets nearby.
Restore power and test the cycle
Turn the breaker back on and let the pump run. Watch the gauge at the house supply while a faucet is open. Pressure should rise to the pump's cut-off point and hold steady when the faucet is closed. Run the water long enough to clear trapped air. If the pump cycles very rapidly, stop and recheck the air charge and the connection before you leave the job.
Final check before you walk away
Confirm the pressure stays steady at several faucets, the pump shuts off cleanly, and there are no leaks at the fittings. Leave the old tank's air reading and the new tank's setting written down with the date of the job. A well contractor can verify the system if you want a second set of eyes on the final test.