A waterlogged or failing pressure tank is one of the leading causes of premature well pump failure, and most homeowners never see it coming until the tap runs dry. No water pressure means no showers, no cooking, no toilet. Every hour without a diagnosis risks burning out your pump motor, a $1,500 to $2,500 replacement that starts with a problem most people fix for $20. The wrong diagnosis, replacing a $300 tank when a single valve had failed, is the most expensive mistake in residential well systems. This article covers every reason a pressure tank is not filling with water, how to confirm the cause in five steps with a tire gauge and your knuckle, and what every fix costs from free to $400. New tank or old tank, the answer is here. Table Of Contents 1. How to Tell If Your Pressure Tank Is Failing 2. How a Well Pressure Tank System Works 3. Why Your Pressure Tank Won't Fill — The Real Causes 4. How to Check Your Pressure Tank Before Calling Anyone 5. What It Costs to Fix a Pressure Tank How to Tell If Your Pressure Tank Is Failing A healthy pressure tank runs quietly. The pump cycles on for one to two minutes, pressure holds steady between uses, and water flows without interruption. These are the seven signs your tank is failing: Short cycling — the well pump clicks on and off every few seconds instead of running a full one to two minute cycle. The tank has lost its air cushion. Every small draw of water causes an instant pressure drop that forces the pump to fire again immediately. Left uncorrected, short cycling can burn out a pump motor within days to weeks. Pressure drops the moment the pump shuts off. Open any tap and pressure falls immediately. The tank has no draw-down reserve left. Faucets spit air and sputter. A torn bladder leaks trapped air directly into the water lines, causing surging at every outlet in the house. The tank feels solid and heavy throughout when tapped. A healthy tank sounds hollow at the top, where the air charge sits. A failing tank feels uniformly dense because water has displaced the air charge completely. The pump runs three to five minutes per cycle to reach cut-out pressure. Normal is under two minutes. The pressure gauge jumps between 20 PSI and 50 PSI repeatedly. Waterlogging removes the air buffer. Pressure spikes to cut-out, the pump shuts off, and pressure drops instantly below 30 PSI because nothing is holding it. The cycle repeats continuously. Rust patches on the steel casing or cloudy water from your taps signal that internal corrosion or sediment disturbance is contaminating the water supply. Stop using the system and call a plumber before running water again. Short cycling burns out the pump motor. A $150 tank problem left unaddressed routinely becomes a $1,500 to $2,500 combined tank and pump replacement. How a Well Pressure Tank System Works A well pressure tank stores compressed air and well water in a single sealed tank, using air pressure to push water through your home without the pump running for every draw. Think of it as a battery for your water supply. It holds energy in the form of compressed air and releases it on demand. Inside the steel shell, a rubber bladder divides the tank into two chambers. Well water fills the inside of the bladder. Compressed air surrounds the bladder on the outside, pressing against it. On vertical tanks, the Schrader valve sits at the top, identical to a car or bicycle tire valve. Use a standard tire gauge on this valve to check and adjust the air charge. The pressure switch controls when the pump runs. In the most common residential setting, 30/50 PSI, the switch turns the pump on at 30 PSI and off at 50 PSI. On a 40/60 system, those numbers shift to 40 PSI and 60 PSI. The system runs in four steps: Usage: Pressure Drops. You open a tap. The air charge pushes water out of the bladder and through your pipes. Tank pressure begins to fall. Pump Triggers: Cut In. Pressure drops to 30 PSI. The pressure switch signals the pump to turn on. Refilling: Pressure Builds. The pump pushes water into the bladder. The bladder expands, compressing the air surrounding it. Pressure climbs back up. Pump Shuts Off: Cut Out. Pressure reaches 50 PSI. The pressure switch shuts the pump off. The drawdown volume is the usable water delivered before the pump kicks on, not the tank’s total capacity. A standard 20-gallon residential tank delivers approximately 5–7 gallons per cycle at a 30/50 setting, about 30% of total tank volume. Larger tanks deliver proportionally more. Without a pressure tank, the pump fires every time you flush a toilet or open a tap, overheating and wearing out the pump motor prematurely. According to the Hydraulic Institute, properly sized pressure tanks reduce pump start frequency by up to 80%, directly extending motor lifespan. The correct air pre-charge is 2 PSI below cut in pressure, 28 PSI on a 30/50 system and 38 PSI on a 40/60 system. When air bleeds out through the Schrader valve over time, the pre-charge drops, the bladder stops expanding correctly, and the tank stops filling. Need Professional Plumbing Help? Our licensed experts are standing by 24/7. Call (416) 383-7378 Why Your Pressure Tank Won't Fill — The Real Causes When a pressure tank is not filling with water, the cause almost always falls into one of five categories: wrong air pre-charge, ruptured bladder, failed pressure switch, failed check valve, or a flow restriction upstream. One of them costs $20 to fix and is routinely misdiagnosed as a $400 tank replacement. Wrong Air Pre-Charge The wrong air pre-charge is the most common cause, in new tanks and in old tanks that have slowly lost air over time. Air pre-charge must be exactly 2 PSI below cut-in pressure. On a 30/50 pressure switch, that means 28 PSI. On a 40/60 pressure switch, that means 38 PSI. When the pre-charge equals or exceeds the cut-in pressure, water cannot physically enter the bladder. New tanks are the most common victims. Manufacturers ship tanks with a default pre-charge that is frequently wrong for the buyer’s pressure switch setting. A homeowner on a 40/60 system installs a new tank, adjusts nothing, and the factory charge blocks water entry from the first minute of operation. Always verify with a tire gauge after full system depressurization. Ruptured Bladder A ruptured bladder is the most common failure in tanks seven years old or older. When the rubber bladder tears, the result is a waterlogged pressure tank with no air buffer left. The pump pushes water in, pressure spikes to cut out almost instantly, collapses the moment a faucet opens, and the pump fires again immediately. The tank feels solid and heavy throughout when tapped with no hollow section at the top and no draw-down water reserve. To confirm, depress the Schrader valve pin after fully depressurizing the system. If air is released, the bladder is intact. If water leaks, the bladder has ruptured and the tank needs full replacement. See our waterlogged pressure tank guide. Two Causes That Look Like Tank Failure (But Aren’t) A failed pressure switch. This stops the pump from starting or shuts it off before the tank reaches cut out. Mineral deposits or carbon scorching on the contact points are the cause. The gauge reads flat zero or stops climbing mid-cycle. Replacement costs $20–$40. See our [pressure switch guide]. A failed check valve. This lets water drain back into the well after every cycle. Pressure drops to zero within 2–3 minutes of the pump shutting off with no taps open. Replacement costs $15–$30. Confirm by watching the gauge drop to zero within 3 minutes of pump shutoff. Two Less Common Causes Sediment coating on the bladder. Iron-rich or hard water deposits stiffen the bladder over months. Drawdown volume shrinks gradually before complete failure. Confirm with a basic water test kit. Clogged sediment filter or failing pump. A blocked inline filter starves water flow to the tank. A degrading pump cannot build pressure past 20 PSI. If all causes above are ruled out, the pump or well needs a professional assessment. How to Check Your Pressure Tank Before Calling Anyone You can check a pressure tank in five steps using a tire gauge and your knuckle. Before touching anything, cut power to the pump at the breaker and open any faucet until flow stops and the pressure gauge reads zero. Checking air charge on a pressurized system gives a false reading every time. Do this before every test, no exceptions. Step 1 — Tap Test Knock the tank firmly from top to bottom with your knuckle. Hollow at the top, dull thud at the bottom — bladder intact Solid throughout — waterlogged Rust patches, corrosion, or bulging on the shell — replacement needed regardless If the result is unclear, move to Step 2. Step 2 — Schrader Valve Test Press the center pin briefly. Air releases — bladder intact Water releases — bladder ruptured, replace the tank Nothing releases — air charge is gone, recharge and retest If the tank loses the recharged air within a few hours, the bladder has a slow leak and needs replacement. Step 3 — Tire Gauge Reading Check the label inside your pressure switch cover for your cut-in setting. The gauge must read exactly 2 PSI below cut-in pressure. 30/50 system — 28 PSI 40/60 system — 38 PSI if the reading is too high, water cannot enter the bladder. If it is too low, add air through the Schrader valve using a bicycle pump or compressor. Step 4 — Pressure Gauge Observation Restore power and open a tap. Watch the gauge. Steady climb to cut-out that holds — system working, problem is elsewhere Drops immediately when tap opens — waterlogging confirmed Climbs slowly, never reaches cut-out — pump underperformance Never moves — pressure switch failed or pump not running Step 5 — Gate Valves and Check Valve Confirm every valve between the well and the tank is fully open. A partially closed gate valve looks open from outside but restricts flow significantly. Check the valve body for a flow arrow pointing away from the well toward the tank. With the pump off and no taps open, pressure dropping to zero within three minutes confirms check valve failure. Three mistakes cause most failed diagnoses. Checking the air charge without depressurizing first always gives a false high reading. Setting the pre-charge equal to the cut-in pressure physically blocks water from entering the bladder. Replacing the entire tank when a $20 check valve had failed is the most expensive misdiagnosis on this list. What It Costs to Fix a Pressure Tank Most pressure tank problems cost $15 to $40 in parts and under an hour to fix yourself. Full replacement runs $100 to $400 for the part, or $300 to $1,000 installed professionally depending on tank size. DIY Repairs — Cheapest to Most Expensive Problem Cost Notes Wrong air charge Free Bicycle pump, ten minutes, any homeowner Check valve failed $15–$30 Most overlooked fix on this list Pressure switch clogged or failed Clean the sensing port first. Replace if contacts are carbon-scorched Ruptured bladder $100–$400 Full tank replacement required Quality brands like Well-X-Trol and WellMate run $150 to $400 and last 10 to 15 years. Budget brands like Flotec and WaterWorker run $80 to $150 and typically fail in 5 to 7 years. DIY replacement saves $250 to $500 in labor. If Hiring a Professional Labor runs $75 to $150 per hour and replacement takes 2 to 4 hours. Most companies charge a $50 to $100 diagnostic fee. If replacing the tank, ask the technician to swap the pressure switch and gauge at the same time. The system is already drained and you pay parts only. Tank Age and Warranty If the tank is 10 years or older, replace it regardless of diagnosis. Repair cost never justifies the remaining lifespan. If the tank is new and under warranty, contact the manufacturer before spending anything. Brands like Amtrol and Goulds cover factory pre-charge defects. A waterlogged tank left unaddressed leads to pump burnout, costing $1,500 to $2,500. If your pump is already showing signs of stress, Everest Plumbing’s sump pump and submersible pump repair service covers emergency assessment and replacement across the Toronto area. When to Call a Licensed Plumber Most pressure tank problems are homeowner-manageable. These five are not. The pump needs pulling from the well casing—submersible pump extraction requires specialized equipment and a licensed well contractor. The pump runs continuously but pressure never climbs past 20 PSI — the well water level may have dropped, requiring professional well assessment. The pressure switch keeps failing after replacement — repeated failure points to an electrical or pump fault beyond the switch itself. The system will not come back online after winter shutdown — frozen lines, cracked fittings, or a seized pump need hands-on diagnosis. The pump ran dry and water returns cloudy, discolored, or air-mixed — a contamination risk that requires water testing before the system is safe to use. Everest Plumbing’s licensed well system specialists serve the Toronto area 24/7. [Book a same-day assessment] — do not run the system until it has been inspected. Frequently Asked Questions 1. Should a pressure tank have water in it? Yes. A healthy pressure tank always contains water, separated from the compressed air by a rubber bladder. If your pressure tank is not filling with water at all, either the pump is not running, or the bladder has ruptured and drained the water side completely. The water occupies roughly 30 to 40% of the total tank volume during normal operation. 2. Why does my well pump keep turning on and off every few seconds? Rapid pump cycling — called short cycling — is caused by a waterlogged pressure tank. The tank has lost its air cushion and can no longer hold draw-down water between pump cycles. Every small water draw causes an instant pressure drop, forcing the pump to fire again immediately. Fix the tank before the pump motor burns out. 3. What PSI should my pressure tank be set to? The air pre-charge must be exactly 2 PSI below the cut-in pressure of your pressure switch. On a 30/50 system, that means 28 PSI. On a 40/60 system, that means 38 PSI. Setting the pre-charge equal to or above the cut-in pressure physically prevents water from entering the bladder. 4. What happens if I ignore a failing pressure tank? Short cycling overheats and burns out the pump motor. A $150 tank problem left unaddressed becomes a $1,500–$2,500 combined tank and pump replacement. The warning signs — short cycling, pressure drops, sputtering faucets — appear weeks before complete failure. Acting on them early prevents the more expensive repair. 5. How much does it cost to replace a pressure tank? DIY tank replacement costs $100–$400 for the part. Professional installation adds $300–$600 for a standard 20–40 gallon tank. Labor runs $75–$150 per hour and most replacements take 2–4 hours. A diagnostic fee of $50–$100 is standard before work begins. DIY replacement saves $250–$500 in labor.
