How to Replace a Well Pressure Tank
To replace a well pressure tank, shut off the pump, drain the system to zero, disconnect the old tank from the tank tee, set the new tank's air charge to 2 psi below your pressure switch cut-in, and pipe it in standing upright. A handy homeowner can do it in an afternoon. The hard parts are corroded fittings and the weight of a full-size tank in a tight basement.
Make sure the tank is the problem
Before you buy, rule out a tank that just needs air. Shut off the pump, drain the system and press the valve core on the tank's air valve. Air means the bladder may be fine and the charge is just low. Water means the bladder has failed, and the tank needs replacing. Short cycling, pressure swings, rust on the outside and a tank that sounds solid when you knock on it are the other common signs. Our pressure tank troubleshooting page walks through each test.
Pick the replacement
Same size or bigger is the safe rule. A larger tank holds more water and lets the pump run less often. HomeGuide's rough household guide is 20 to 40 gallons for 1 to 2 people, 40 to 60 gallons for 3 to 4, and 80 gallons or more for larger households. The better way is to size from your pump's flow rate, which Amtrol's sizing card does. Our page on what size pressure tank you need explains how.
Check the new tank's factory pre-charge. Amtrol's Well-X-Trol tanks ship at 38 psi, which only suits a 40/60 switch, so you'll adjust it either way. And confirm the tank's pressure rating clears your system. Well-X-Trol tanks are rated to 150 psi.
Tools and parts
- The new tank
- A new tank tee, or at least new fittings, if the old ones are corroded
- A new pressure gauge and relief valve if the old ones are old or crusty
- A new 1/4-inch nipple for the pressure switch, since that little pipe clogs with sediment and rust
- Pipe wrenches, thread sealant tape or pipe dope rated for drinking water
- A tire pressure gauge and an air compressor or bike pump
- A hose and bucket for draining
- A helper or a hand truck for the old tank
Step by step
Shut off the pump breaker
Confirm the pump won't run.
Close the main valve to the house
That keeps the house plumbing from draining back into the tank while you work.
Drain the tank
Open the drain at the tank tee or a nearby faucet and let it run until the gauge reads zero and the flow stops.
Disconnect the old tank
Unscrew it from the tank tee or the pipe that feeds it. Hold the fitting behind it with a second wrench so you don't twist the piping. Tip the tank to drain the last of the water before you move it.
Set the new tank's air charge before it touches water
Release or add air so the pre-charge is 2 psi below your pressure switch cut-in. Amtrol says to do this at room temperature. Our air pressure guide has the details.
Place the new tank
Amtrol's instructions call for it to stand vertically on a surface that can carry its full weight with water, as close to the pressure switch as possible. Keep it out of direct sunlight and anywhere it could freeze.
Plumb it in
Wrap the threads, connect the tank to the tee, and reinstall the switch, gauge, relief valve and drain on the tee. Amtrol says the lines from the pump to the tank and the switch should be the same size, to prevent switch cycling. Replace the switch nipple now while it's easy.
Check for a relief valve and drip pan
Amtrol calls for a relief valve at the tank connection to protect the tank if the pressure switch fails, and a drip pan piped to a drain wherever a leak could cause damage.
Restore power and fill
Close the drain, turn on the breaker and let the pump run until it cuts off. Check every joint for drips.
Open the house valve and flush
Open the main valve slowly, then run the laundry tub faucet and any taps without aerators first to purge air and sediment.
Watch a full cycle
Run water until the pump kicks on, then shut it off and watch it stop at the cut-out. The pump should run noticeably longer than it did with the old tank.
Mistakes to avoid
- Skipping the pre-charge check. A factory charge that doesn't match your switch means short cycling from day one.
- Reusing the crusty tank tee. Corroded fittings are the next leak, and the system is already drained.
- Laying a tank on its side. Amtrol's residential tanks are made to stand vertically only.
- Setting it where a leak would ruin the room. Amtrol warns against locating tanks where a leaking tank or connection could cause property damage unless there's a drip pan to a drain.
- Forgetting the pump. If the old tank was waterlogged for a long time, the pump took a beating. Keep an eye on how it starts.
When it's a pro job
Hire a well contractor or plumber if the tank is in a well pit, buried, or in a crawlspace you can barely reach, if the fittings are badly corroded, or if the switch wiring looks scorched. HomeGuide's 2025 figures put a professional replacement at $800 to $1,500 for most homes, with labor alone at $250 to $500 or more. The full breakdown is on our pressure tank replacement cost page.
FAQ
Can I replace a well pressure tank myself?
Yes, if you can shut off the pump circuit safely and do basic threaded plumbing. The key steps are draining the system to zero, setting the air charge before installation, and standing the tank upright near the switch. If the fittings are seized or the space is tight, a pro is worth it.
Where should a well pressure tank be placed?
Amtrol says as close as possible to the pressure switch, standing vertically on a floor that can carry its full weight. Keep it where it won't freeze or sit in direct sun, and where a leak won't damage the house.
Is a 20 gallon pressure tank big enough for a house?
For one or two people it can be. HomeGuide's guide puts 20 to 40 gallons in that range. Amtrol's 20-gallon WX-202 gives about 5.4 gallons of drawdown at 40/60, and its sizing card matches it to a small pump of about 5 gallons per minute. Bigger households and bigger pumps need a bigger tank.
How much does it cost to install a pressure tank on a well?
HomeGuide puts most installs at $800 to $1,500, with a national average around $1,000. Size, access and the extra parts replaced at the same time move the price.
Sources
- AMTROLWell-X-Trol Residential Pre-Pressurized Well Tanks Installation and Operation Instructions (opens in a new tab)
- AMTROLWell-X-Trol Well Tanks (opens in a new tab)
- Boshart IndustriesAdjusting the Pre-Charge Pressure of a Captive Air Tank, Bladder or Diaphragm Type Tanks (opens in a new tab)
- HomeGuideHow Much Does It Cost to Replace a Well Pressure Tank? (opens in a new tab)
- AMTROLWell-X-Trol Quick Sizing Guide (opens in a new tab)
- Boshart IndustriesWhy won't my pressure switch turn on? (opens in a new tab)