Pressure tank calculator
What should my tank’s pre-charge be?
Cut-in minus 2 PSI is the industry-standard rule, checked with the system fully drained.
Set your pre-charge to 28 PSI.
Measured with the pump off and the system drained to 0 PSI, using an ordinary tire gauge. If your tank came with a manual, follow its figures; this is the industry standard, but your manufacturer has the final word.
If the tank has lost its air, the tank maker’s rule is that re-charging it is a job for a professional, unless the tank is new or confirmed free of corrosion.
This procedure doesn’t apply to old galvanized air-over-water tanks with no air valve on top. They have no bladder and need a different reset.
Short cycling, weak pressure, or a pump that won’t behave? Run Pressure Fix. It takes a few questions and no signup.
This tool offers general guidance based on published industry sources. It is not professional plumbing or well-service advice, and it can’t see your actual system. Follow your equipment manufacturer’s manual where you have it, and when in doubt (especially around electricity, pressure vessels, or anything urgent) stop and call a licensed professional.