Vertical pressure tank connected to a water pump outdoors

Replace and install a well pressure tank

A bladder or diaphragm pressure tank stores water under an air charge so the pump does not start every time a tap opens. Replacing one is a plumbing job at the tank tee, but the step that decides whether it works is setting the air precharge with the system at zero pressure, a little below the pressure switch cut-in. Size the tank and tee to the pump and follow the tank maker's instructions.

Cross-checked ~180 min moderateBrands: All

Before you start

Turn off the pump breaker and verify dead at the pressure switch before touching the plumbing; well pumps are often 240 V.
Relieve all water pressure before loosening any fitting at the tank tee.
Full pressure tanks are very heavy; drain before moving and get help.
Any change to the pump circuit or a new disconnect is work for a qualified electrician where required by local code.

Diagnostic steps

Unlock all 10 steps with expected values

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