Pressure tank replacement
The cheapest part in the system, and the one whose failure quietly destroys the most expensive part.
A well pressure tank should be replaced when it has become waterlogged, meaning it has lost the air charge that lets it hold pressure. The giveaway is rapid pump cycling, where the pump starts and stops every few seconds while water runs. Replacing it is one of the least expensive jobs on a well system, and skipping it is one of the most reliable ways to destroy a pump.
What the tank is actually for
A pressure tank is not storage. It is a shock absorber.
Inside is a rubber bladder or diaphragm with compressed air on one side and water on the other. When the pump runs, water pushes in and compresses the air. When you open a tap, that compressed air pushes water back out. The pump does not need to start.
Without a working tank, every tap you open starts the pump. Motor starts are what wear a submersible pump out, not running hours. A pump that would have lasted twelve years can fail in two or three if it is cycling constantly.
That is the whole argument for fixing this part promptly. The tank is the cheap component protecting the expensive one sitting 300 feet underground.
How to check yours
Listen for the cycle. Run a tap at a steady moderate flow and listen to the pump. It should run, fill, and shut off, then stay off for a while. If it starts and stops repeatedly within seconds, the tank is not doing its job. See pump runs constantly or short cycles.
Tap down the side. Knuckles work. Hollow at the top, dull and solid at the bottom, with a clear transition, means the tank still has an air cushion. Solid the whole way up means it is full of water.
Check the air valve. There is a valve on top that looks like a tire valve. With the system depressurized, it should read roughly 2 psi below the pump’s cut-in pressure. Water coming out of that valve instead of air means the bladder has ruptured and the tank needs replacing.
Watch the gauge. A pressure gauge that swings rapidly between cut-in and cut-out while a tap runs is showing you the same problem the pump sound is.
What replacement involves
The job is short compared with anything involving the well itself:
- Power off at the breaker, then drain the system pressure
- Disconnect the old tank from the tee and remove it
- Set the air charge on the new tank to match the pressure switch settings
- Install the new tank, usually with new fittings and a new gauge
- Repressurize, purge air from the lines, and verify the cycle
Most of the cost is the tank itself, the fittings, and an hour or two of labor. Bigger tanks cost more but give longer pump cycles, which is the point.
Two things are worth doing at the same time while the plumbing is open. Replace the pressure switch if it is old, since it is inexpensive and sits right there. And replace the gauge, because an unreadable gauge makes every future diagnosis harder.
Sizing, in plain terms
The relevant number is drawdown, meaning how much water the tank actually delivers between the pump shutting off and starting again. That is much less than the tank’s physical volume.
| Tank behavior | What it means for the pump |
|---|---|
| Undersized tank | Short, frequent cycles. Hardest on the motor |
| Correctly sized | Pump runs a reasonable stretch, then rests |
| Oversized | Longer cycles, more space used, no harm to the pump |
Erring larger is the safer direction if you have the room for it. The tank is not where you save money on a well system.
Water quality shortens tank life
Sediment and hard water are both hard on tanks, and both are common on wells in this area. A 2026 Arizona State University study of 47 private wells in Yavapai County found 45% exceeded EPA limits for hardness and 10% showed turbidity. Sediment settles inside a tank and abrades the bladder. Scale builds on fittings and gauges.
If you are replacing a tank that failed early, it is worth testing the water to find out whether something in it is the reason. See well water testing and what is actually in Yavapai County well water.
Next step
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Common questions
How do I know if my pressure tank is bad?
The clearest sign is rapid cycling, where the pump kicks on and off every few seconds while a tap runs. Tap the tank as well. A healthy tank sounds hollow toward the top and solid toward the bottom. One that sounds solid all the way up has lost its air charge and is waterlogged.
Why does a bad pressure tank matter if I still have water?
Because it kills pumps. The tank exists so the pump can run in reasonable cycles instead of starting every time you open a tap. When the tank fails, the pump starts and stops constantly, and motor starts are what wear a pump out. A cheap tank failure left alone becomes an expensive pump failure.
Can a pressure tank be recharged instead of replaced?
Sometimes. If the bladder is intact and the tank has simply lost air pressure, it can be recharged to the correct setting, usually 2 psi below the pump cut-in pressure. If the internal bladder has ruptured, the tank is finished and recharging will not hold.
What size pressure tank do I need?
It depends on the pump's flow rate and the run time you want. Bigger tanks mean longer, less frequent pump cycles, which is easier on the pump. Undersizing to save money on the tank is a false economy given what a pump costs.
How long do pressure tanks last?
Commonly a decade or more, though it varies with water quality and cycling. Sediment and hard water shorten it. If yours is original to a house built in the 1990s, it is living on borrowed time.
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