Amtrol WX-202 — 20-Gallon Pre-Charged Pressure Tank (Well-X-Trol)

What is it and what's it for?

Think of it as the system's 'water shock absorber': a rubber bladder (the diaphragm) inside a metal tank fills with pressurized water every time the pump runs, like a balloon inflating. When you open a faucet, water comes out of that pressurized balloon first, not straight from the pump — so the pump doesn't have to switch on every time someone opens a faucet for two seconds, only when the tank's reserve actually runs low.

Real-world use cases

• At home: You installed the WAYNE SWS50 or the Red Lion from this ranking along with the Square D pressure switch, but without this tank the pump turns on and off every few seconds the moment someone opens a faucet — add the tank and the pump only kicks on a handful of times a day instead of hundreds.
• In a business or workshop: A plumber installing residential well systems knows an undersized tank is the number-one cause of pump motors burning out early from short-cycling — picking the right size upfront saves the customer a warranty callback a few months later.

How to avoid buying the wrong one

• This tank's factory pre-charge is 38 PSI — it needs to sit 2 PSI below your switch's 'cut-in' pressure. If your switch is 40-60 PSI (like the Square D FSG2J24CP in this ranking), this tank already ships calibrated correctly; if yours is a different range, you'll need to readjust the pre-charge with a tire pump before installing it.
• 20 gallons is the standard residential size, but the actual usable volume (drawdown) is considerably smaller — if your home has multiple bathrooms or appliances drawing water at once, work out how many gallons per minute you need to sustain before assuming this size is enough; the Well-X-Trol family also comes in larger sizes.
• This model's connection is 1" NPT — confirm it matches your installation's piping before buying, or you'll need a thread adapter.