Signs of a Waterlogged Pressure Tank
Signs of a Waterlogged Pressure Tank — Deep Dive Plumbing Maryland
If your well pump is turning on and off every 30 seconds, you almost certainly have a waterlogged pressure tank. Here's how to recognize it, test it yourself, and understand why it matters.
What Is a Pressure Tank and What Does It Do?
A pressure tank is a steel or fiberglass vessel installed between your well pump and your home's plumbing. Inside is a rubber bladder or diaphragm that separates a pre-charged air cushion from the water side. When the pump runs, it fills the water side of the tank, compressing the air. That compressed air is what maintains water pressure in your home between pump cycles.
A properly functioning pressure tank stores 5–10 gallons of pressurized water. This means your pump only needs to run when the tank is depleted — typically every few minutes during normal use. A waterlogged tank stores almost no water, so the pump must start every time you open a faucet.
6 Signs Your Pressure Tank Is Waterlogged
Pump Short-Cycling
The pump turns on and off every 30 seconds or less. A healthy pressure tank stores 5–10 gallons of pressurized water, allowing the pump to run in long, efficient cycles. A waterlogged tank holds almost no air — the pump must start every time you open a faucet.
Pressure Gauge Swings Wildly
Watch your pressure gauge when running water. A healthy system holds pressure in a steady range (typically 40–60 PSI). A waterlogged tank causes the gauge to swing rapidly from cut-in to cut-out pressure with every pump cycle.
Pump Runs Constantly
In severe cases, the pump runs without stopping. This happens when the bladder has completely failed and the tank is 100% full of water — there's no air cushion at all, so the pump can never build enough pressure to shut off.
Knocking or Banging Pipes
Water hammer — the banging noise in your pipes when a faucet is turned off — is caused by sudden pressure changes. A waterlogged tank can't absorb pressure spikes, causing the shock wave to travel through your plumbing.
Fluctuating Water Pressure
You notice pressure dropping significantly when multiple fixtures run simultaneously, or pressure surging when the pump kicks on. This is the tank failing to maintain a steady pressure buffer.
Climbing Electric Bill
A pump that short-cycles starts hundreds of times per day instead of dozens. Each motor start draws 3–5 times the running current. The result is a noticeably higher electric bill — often $20–$50/month more than normal.
Why Short-Cycling Destroys Well Pumps
Every time a submersible pump starts, it draws 3–5 times its running current for a fraction of a second. This startup surge generates heat in the motor windings. A pump that starts 500 times per day (short-cycling) generates far more heat than one that starts 50 times per day. Over weeks and months, this heat degrades the motor insulation and burns out the windings. A waterlogged pressure tank is one of the top causes of premature well pump failure.
How to Test Your Pressure Tank Yourself
You can do a quick field test in two minutes:
What Causes a Pressure Tank to Become Waterlogged?
Most modern pressure tanks use a rubber bladder or diaphragm to separate the air charge from the water. Over time, this bladder fails — it develops a pinhole, tears, or simply loses elasticity. Once the bladder fails, water fills the entire tank and the air charge is lost.
Bladder failure is accelerated by poor water quality. High iron content in Maryland well water is particularly damaging — iron deposits on the bladder surface, making it brittle and prone to cracking. Acidic water (low pH) also degrades rubber over time. A quality pressure tank lasts 10–15 years with good water quality; in areas with high iron or low pH, 5–8 years is more realistic.
Can You Fix a Waterlogged Pressure Tank?
If the bladder has failed, the tank must be replaced — there is no repair. Bladder replacement is not practical or cost-effective. A new pressure tank installed runs $400–$900 depending on size.
If the bladder is intact but the pre-charge pressure is low (the tank has lost its air charge without bladder failure), you can add air through the Schrader valve. The correct pre-charge pressure is 2 PSI below the pump cut-in pressure — typically 38 PSI for a 40/60 pressure switch. This is done with the pump off and the system depressurized.