Waterlogged Pressure Tank
Is Your Pump Short-Cycling? Act Fast.
A waterlogged pressure tank causes your well pump to short-cycle — turning on and off every few seconds. This is the leading cause of premature pump motor failure. Deep Dive Plumbing Maryland diagnoses and replaces waterlogged tanks throughout Southern Maryland.
How a Pressure Tank Works — And What Goes Wrong
A pressure tank contains a rubber bladder that separates an air charge from the water. When the pump runs, water fills the tank and compresses the air charge. When you open a faucet, the compressed air pushes water out of the tank — maintaining pressure without the pump running. The pump only turns on when the pressure drops to the cut-in setpoint (typically 40 PSI).
When the bladder fails, water fills the entire tank with no air cushion. Now every time any water is drawn — even a single cup — the pressure drops immediately and the pump turns on. The pump turns off as soon as the pressure reaches the cut-out setpoint (typically 60 PSI), which happens almost instantly with no tank volume to fill. Then the pressure drops again and the pump turns on again. This cycle repeats every few seconds.
Each pump start draws 3–5 times the normal running current. A pump that short-cycles 500 times per day is experiencing enormous electrical stress. Most pump motors fail within weeks to months of a bladder failure if the tank is not replaced.
Symptoms of a Waterlogged Pressure Tank
How We Diagnose a Waterlogged Tank
The Tap Test
We tap the tank from bottom to top with a coin or knuckle. A healthy tank sounds hollow (air) in the upper portion and solid (water) in the lower portion. A waterlogged tank sounds solid throughout.
Schrader Valve Check
With the pump off and pressure relieved, we check the Schrader valve at the top of the tank. If water comes out instead of air, the bladder has failed.
Cycle Count
We count how many times the pump cycles per minute during normal water use. More than 2–3 cycles per minute indicates a waterlogged tank or undersized tank.
Pressure Gauge Reading
We monitor the pressure gauge during pump cycling. A healthy system shows a gradual pressure rise and fall. A waterlogged system shows rapid pressure swings.
Recent Job — Owings, MD
In Owings, a homeowner called because their pump was running every 30 seconds — they could hear it clicking on and off constantly from the basement. The pump was only 4 years old.
We diagnosed a waterlogged 20-gallon pressure tank — the bladder had failed and the tank was completely full of water with no air cushion. The pump was short-cycling hundreds of times per day.
We replaced it with a properly sized 44-gallon tank and set the pre-charge pressure correctly. The pump now cycles normally — 2–3 times per hour instead of every 30 seconds. We also installed a Pump Saver to protect the pump from any future dry-run damage. The pump has been running reliably ever since.
Pressure Tank FAQs
What is a waterlogged pressure tank?
A pressure tank contains a rubber bladder (or diaphragm) that separates the air charge from the water. The air charge acts as a cushion — it compresses as water fills the tank and expands as water is drawn out, maintaining pressure between pump cycles. When the bladder fails, water fills the entire tank with no air cushion. The pump must then turn on and off every time any water is used — even a single cup — because there is no stored pressure.
What does short-cycling mean?
Short-cycling means the pump turns on and off very rapidly — sometimes every 5–10 seconds. This happens because a waterlogged tank has no air cushion to maintain pressure between pump cycles. Every time any water is drawn, the pressure drops immediately and the pump turns on. The pump motor is not designed to start and stop hundreds of times per day — each start draws 3–5 times the normal running current, generating heat that destroys the motor windings.
How do I know if my pressure tank is waterlogged?
The tap test: tap the tank with a coin or your knuckle from bottom to top. A healthy tank will sound hollow (air) in the upper portion and solid (water) in the lower portion. A waterlogged tank will sound solid throughout — all water, no air. You can also check the Schrader valve (like a tire valve) at the top of the tank with the pump off and pressure relieved — if water comes out instead of air, the bladder has failed.
Can I fix a waterlogged pressure tank myself?
You can try re-pressurizing the air charge through the Schrader valve, but if the bladder has failed, the air will simply push through the bladder into the water and escape. The only real fix for a failed bladder is tank replacement. Some tanks have replaceable bladders, but in most cases it is more cost-effective to replace the entire tank — especially since a failed bladder usually means the tank is at the end of its service life.
How long do pressure tanks last?
A quality pressure tank typically lasts 10–15 years. Factors that shorten tank life include: water with high iron or mineral content that corrodes the tank interior, incorrect pre-charge pressure (the air charge should be set to 2 PSI below the pump cut-in pressure), and water hammer from rapid pump cycling. We recommend checking the pre-charge pressure annually as part of a well system inspection.
What size pressure tank do I need?
Pressure tank sizing depends on your pump's horsepower and the pressure switch settings. A common mistake is replacing a failed tank with the same size — which may have been undersized to begin with. An undersized tank causes more frequent pump cycling even when the bladder is healthy. We size replacement tanks based on your pump's flow rate and the desired cycle time to maximize pump life.
Can a waterlogged tank damage my well pump?
Yes — this is the most important reason to address a waterlogged tank immediately. Short-cycling is the leading cause of premature well pump motor failure. Each pump start draws 3–5 times the normal running current. A pump that short-cycles 500 times per day is experiencing the electrical stress equivalent of running for days of normal operation. Most pump motors fail within weeks to months of a bladder failure if the tank is not replaced.
How much does pressure tank replacement cost?
Pressure tank replacement in Southern Maryland typically costs $400–$900 depending on tank size and accessibility. This is a fraction of the cost of a well pump replacement ($1,500–$3,500) — which is why addressing a waterlogged tank immediately is so important. We provide free estimates — call (443) 440-0632.
Is Your Pump Short-Cycling?
Don't wait — short-cycling destroys pump motors. Call Deep Dive Plumbing Maryland for same-day pressure tank diagnosis and replacement.