The pressure tank does most of the work in a private well system. Without it, the well pump would kick on every time someone opens a tap. The tank holds water under air pressure between pump cycles. When the air pre-charge is wrong or the bladder ruptures, the pump short-cycles — turning on and off many times per hour instead of the normal 6 to 8 times — and pump life drops from 15 to 20 years to as little as 1 to 2 years. A yearly air pressure check is the cheapest insurance on the most expensive component of a private well system.
Quick check (yearly)
- Turn off power to the well pump at the breaker or disconnect.
- Open a faucet (preferably an outdoor spigot or a sink with a hose) to drain pressure from the system. Let it run until water stops.
- Find the Schrader valve (looks like a tire valve) on top of the pressure tank.
- Remove the cap and put a tire pressure gauge on the valve.
- Read the pressure.
What you find tells you the state of the tank:
- Air comes out with a pressure reading: bladder is intact. Compare to target.
- Water sprays out: bladder has ruptured. Tank needs replacement.
- Air comes out but pressure is well below target: bladder is intact but air has leaked over time. Recharge.
What the pre-charge should be
The air pre-charge sets 2 psi below the pressure switch cut-in (the lower number of the switch range).
- 30/50 pressure switch: pre-charge to 28 psi.
- 40/60 pressure switch: pre-charge to 38 psi.
- 20/40 pressure switch (less common): pre-charge to 18 psi.
- 50/70 pressure switch (larger systems): pre-charge to 48 psi.
The pressure switch is the small box on or near the tank that turns the pump on and off. The cut-in/cut-out numbers are marked on it. If you can't tell, check the well's documentation or call a well professional.
How to recharge the air pre-charge
If pressure is low but the bladder is intact:
- With the pump still off and system drained (faucet open), connect a bicycle pump or air compressor to the Schrader valve.
- Add air slowly. Check pressure every 5 to 10 pumps.
- Stop when you reach the target pressure (2 psi below cut-in).
- Don't over-pressurize. Too much pre-charge reduces draw-down volume and short-cycles the pump from the other direction.
- Replace the valve cap.
- Close the faucet.
- Turn the pump breaker back on.
- The pump will run until system pressure reaches cut-out.
- Confirm the pump cycles normally (kicks on at cut-in, off at cut-out, with reasonable runtime in between).
Signs the bladder is failing
- Short cycling: pump turns on and off every few seconds during water use. Most common symptom.
- Tap test sounds solid: a healthy tank sounds hollow at the top and solid at the bottom when tapped with a knuckle. A waterlogged tank sounds uniformly solid.
- Water sprays from the Schrader valve when you press the gauge on. Definitive sign.
- System pressure swings widely during use even though the pump is working.
- Pump runs more often than expected for the household's water use.
- Tank is unusually heavy when bumped. A waterlogged tank weighs much more than a healthy one.
Why this matters so much
A well pump rated for 15 to 20 years of normal cycling (6 to 8 cycles per hour during use) can fail in 1 to 2 years when waterlogged tanks force 30 to 60 cycles per hour. Pump replacement costs $1,500 to $3,500 depending on depth and access. Pressure tank replacement is $500 to $1,500 typically.
Catching a waterlogged tank early and replacing the tank saves the pump.
What you can do yourself vs hire
- DIY appropriate: yearly air pre-charge check with a tire gauge. Adding air with a bike pump or small compressor.
- Hire a pro: pressure tank replacement (involves disconnecting plumbing and electrical), well pump replacement, pressure switch replacement, well casing or sanitary seal work.
- Hire a pro for diagnosis if you're not sure whether the issue is the tank, the switch, the pump, or the well itself.
What changes the schedule
- Tank age: bladder tanks last roughly 5 to 15 years depending on quality and water chemistry. Older tanks need checking more often.
- Water with high iron or sediment: shortens tank life and may shorten bladder life.
- Variable speed pump system: some setups use smaller tanks; check the manual.
- Tankless or constant-pressure systems: no pressure tank, no check needed (different system entirely).
Common mistakes
- Checking pressure with the pump running. The reading is wrong; system pressure is higher than the air pre-charge.
- Over-charging the tank to "give it more air." Reduces water capacity; pump short-cycles.
- Recharging a tank with a ruptured bladder. Air just bleeds through into the water. The tank needs replacement, not recharging.
- Ignoring short cycling because "the water still works." It does, until the pump dies.
- Replacing the pump without checking the tank. The new pump will short-cycle and fail too.
If you're not sure what kind of tank you have
- Bladder/diaphragm tank: most modern residential tanks. Has a Schrader valve on top. The check above applies.
- Galvanized/air-over-water tank: older style, no bladder. The tank holds air and water together, with the air gradually absorbing into the water. These need periodic draining and refilling to reset the air-water ratio. Mostly being replaced by bladder tanks during upgrades.
- Constant-pressure / variable speed system: uses a much smaller tank or no tank at all. Different maintenance.
If you're not sure, take a photo and ask a well professional. Most will diagnose by photo without a service call.
Good maintenance rhythm
- Yearly: check air pre-charge with a tire gauge.
- Yearly: tap the tank from top to bottom to check sound (hollow up top is healthy).
- Quarterly: listen for short cycling during water use. Pump should run for 30+ seconds at a time, not for 5 to 10 seconds.
- If short cycling appears: check tank pre-charge, then call a well pro if not resolved.
- Every 5 to 10 years: have a well pro inspect the full system (pump, tank, switch, wiring).
- If the tank is older than 10 years and showing any symptoms: plan for replacement before failure.
- After any electrical work or storm: confirm pump cycles normally.