How To Check Pressure In Well Pressure Tank: Complete Step-by-Step Guide
Checking the air pressure in your well pressure tank is an essential annual maintenance task that prevents pump short-cycling, extends the life of your submersible or jet pump, and maintains consistent household water pressure. To get an accurate reading, you must completely drain the system of water so that the pressure bladder or diaphragm is fully relaxed against the tank wall.
Pre-Operation & Equipment Checklist
Proper preparation ensures you do not damage your well system or skew your diagnostic measurements. A standard well pressure check requires specific tools and baseline knowledge of your system's operational switch parameters.
- Essential Gear and Tools: Standard tire pressure gauge (digital or dial), heavy-duty bicycle floor pump or portable air compressor, clean rag, pipe thread tape (if replacing Schrader valve cores), and a bucket.
- Mandatory Prerequisite Knowledge: You must know your pressure switch cut-in setting—typically 30/50 or 40/60 pounds per square inch (psi). The correct air charge in the tank must always be exactly 2 psi below your pump's cut-in pressure (e.g., 28 psi for a 30/50 switch, or 38 psi for a 40/60 switch).
- Budget and Duration: Total cost is zero if you already own a gauge and pump. The procedure takes approximately 20 to 30 minutes from start to finish.
Step-by-Step Well Tank Pressure Inspection
Executing this diagnostic procedure requires strict adherence to sequence to ensure the bladder is unloaded and the true pneumatic pressure can be measured and adjusted.
Step 1: Disconnect Power to the Well Pump
Locate the dedicated circuit breaker in your main electrical panel that supplies power to the well pump and flip it to the OFF position.
Warning: Never test or adjust tank air pressure while the pump has power and the system is pressurized with water, as this can lead to bladder rupture or electrical shock hazards if wiring is exposed.
Step 2: Open the Lowest Faucet to Drain the System
Go to the lowest point in your home (such as a basement utility sink, outdoor spigot, or laundry drain faucet) and open it completely. Allow all the water to drain out of the plumbing lines and the pressure tank.
Pro-Tip: Leave this lowest faucet wide open throughout the entire testing and inflation process. This ensures that any residual water inside the tank bladder continues to escape as you adjust the air pressure.
Step 3: Locate the Air Valve and Remove the Cap
Find the air valve on your pressure tank, which looks identical to a standard automotive tire Schrader valve. It is typically located either on top of the tank or underneath a plastic protective cover on the side. Unscrew the valve cap and wipe away any dust or moisture.
Step 4: Measure the Pre-Charge Air Pressure
Press your standard tire pressure gauge firmly onto the Schrader valve stem and take a reading. Compare this measured psi against your pressure switch cut-in threshold (remembering the golden rule: tank air must be 2 psi below the cut-in pressure).
Step 5: Adjust the Air Pressure (Inflate or Bleed)
If the pressure is too low, use your bicycle pump or air compressor to add air until it reaches the target psi (e.g., 28 psi for a 30/50 switch). If the pressure is too high, use a small nail or the tip of your pressure gauge to depress the center pin of the Schrader valve and bleed out excess air in short bursts.
Step 6: Test for a Water-Logged Tank (Bladder Failure Check)
While adjusting the pressure, observe the Schrader valve closely. If water sprays out of the valve stem instead of air, your tank's internal bladder or diaphragm has ruptured, and the entire pressure tank must be replaced immediately.
Step 7: Restore System Operation
Replace the Schrader valve cap securely. Close the lowest household faucet that you left open during the draining process. Finally, turn the circuit breaker back ON to restore power to the well pump, and verify that the pump cycles normally as it refills the tank.
What Pressure Should My Well Tank Be? | Angi
Pressure Switch Settings and Target Air Charge Matrix
| Pressure Switch Setting (Cut-In / Cut-Out) | Target Tank Air Charge (Cut-In Minus 2 PSI) | Symptoms of Incorrect Pressure |
|---|---|---|
| 20 / 40 PSI | 18 PSI | Low water pressure, sluggish flow |
| 30 / 50 PSI | 28 PSI | Pump rapid-cycling, motor burnout |
| 40 / 60 PSI | 38 PSI | Water hammer, fluctuating pressure |
| 50 / 70 PSI | 48 PSI | Extreme pipe vibration, switch failure |
Common Well Tank Failures and Field Fixes
- Root Cause: The tank air pressure drops rapidly within days of being adjusted, but no water is coming out of the Schrader valve.
- Actionable Fix: The Schrader valve core is leaking. Spray a soapy water solution over the valve stem; if bubbles form, tighten the core with a valve tool or replace it entirely using a standard automotive valve core.
- Root Cause: The well pump turns on and off rapidly every single time a faucet is opened just a crack.
- Actionable Fix: The tank is completely water-logged due to a lost air charge or a compromised bladder. Shut off power, drain the system completely, and re-establish the correct air pre-charge. If it fails to hold air, replace the pressure tank.
- Root Cause: The pump refuses to shut off, running continuously while struggling to build pressure.
- Actionable Fix: Check for a stuck pressure switch contact point clogged with sediment, or a major plumbing leak downstream. Clean the switch contacts with fine sandpaper or replace the pressure switch assembly.
Frequently Asked Questions
How often should I check the air pressure in my well tank?
You should check your well pressure tank air charge at least once or twice a year. Regular inspections catch minor air loss early, preventing premature pump wear and costly emergency plumbing repairs.
What happens if the pressure tank air pressure is too high?
If the air pre-charge is set higher than necessary, your usable drawdown capacity decreases significantly. This forces the well pump to turn on and off rapidly every time you run water, causing severe motor strain and short-cycling.
What happens if the pressure tank has zero air pressure?
When a tank loses all of its air charge, it becomes entirely water-logged. The pump will switch on immediately every time a single drop of water is used, drastically shortening the lifespan of the well pump motor and switch contacts.
Can I use a standard bicycle pump to check and fill my well tank?
Yes, a standard hand-operated bicycle floor pump works exceptionally well for well pressure tanks. Because the air volume required to adjust a tank is minimal, a manual pump allows you to add air in controlled increments without overshooting your target psi.
How do I know if my well pressure tank bladder is broken?
A ruptured bladder allows water to mix with the air chamber. If you press the pin on the Schrader valve and water squirts out, the internal barrier has failed and the pressure tank must be replaced.
Protect your home water system by performing routine annual maintenance and keeping your well pressure tank properly calibrated. Bookmark this guide for your next seasonal plumbing checklist or contact a licensed well technician if you suspect a major system failure.
