Best well pressure tank: Amtrol, Water Worker, Goulds, Pentair, Wellmate and Reliance by maker spec sheet, sized on drawdown against pump GPM rather than the gallon label

If the pump short-cycles and nobody has put a tire gauge on the tank’s Schrader valve yet, this is the wrong page: start with the pre-charge check in the well pressure tank cross-reference and come back only if the tank will not hold air.

How was this shortlist built?

Every figure here is a manufacturer-published specification read on 2026-10-09 from the document named beside it. Nothing was installed, pressurised or run by this site, and every listing was confirmed in stock the same day. Tanks were compared on volume, drawdown at 30/50 and 40/60 psi, factory pre-charge, connection, maximum working pressure and construction.

Drawdown is the water the tank delivers between the pump cutting in and cutting out. Pre-charge is the air pressure in the empty tank, read at the Schrader valve with the water drained.

Three gaps are stated, not filled: Water Worker’s guide prints no pre-charge, pressure rating or construction type, Pentair’s WellMate table prints drawdown with no pressure range, and Reliance’s PMD-20 page and State’s brochure print no drawdown at all.

How do the tanks compare on paper?

Every cell is the maker’s own figure; where the document prints nothing, the cell says so.

Goulds is the only maker in this table whose brochure names a certifier and a standard together: NSF Certified to NSF/ANSI 61-G. State prints NSF 61G/372 lead-free wording for the SPMD connection only, with no certifier named for the tank. The Flexcon and Red Lion rows live on the cross-reference page.

How do you size the tank from the pump?

Size on drawdown against the pump’s GPM, with a minimum run time per start. The sources do not print the same split, so each is given as written.

Run time matters because of the start count: Water Well Journal puts the limit at fewer than 300 starts per 24 hours for motors under 1 HP, and Amtrol’s manual says the larger the tank, the less the pump needs to run.

The pump’s GPM is on its nameplate or the installer’s invoice. The switch pair is on the switch label, and the pressure switch page shows which Square D model carries which pair. If the pump will not start at all, the well pump not working guide comes first.

Reliance PMD-20: buy it or skip it?

Buy it if the 20-gallon class is all the space allows and the lowest tier matters more than a published drawdown figure. Reliance’s product page lists 20 gallons of rated storage, a 1 in connection at the bottom, a 100 psi maximum working pressure, a parabolic diaphragm and a 5-year limited warranty.

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The flaw is the missing number: neither the Reliance page nor State’s brochure for the same diaphragm family prints a drawdown figure. State’s brochure does print a 38 psi pre-charge and a butyl parabolic diaphragm for its SPMD and SSB tanks.

Skip it if pressure headroom matters: 100 psi is the lowest working-pressure rating on this page, against 150 psig for every Well-X-Trol.

Amtrol Well-X-Trol WX-202: buy it or skip it?

Buy it if a 5 GPM pump up to 3/4 hp sits on a 40/60 switch and the tank goes on a 1 in tank tee. Amtrol’s spec card prints 20.0 gallons, 6.2 gallons of drawdown at 30/50 and 5.4 at 40/60, a 150 psig working pressure and a 38 psig factory pre-charge, and its manual prints a 7-year limited warranty on WX models.

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The flaw is 5.4 gallons at 40/60: within a hair of the Water Worker HT-20B’s 5.35, and the WX-202XL at 7.0 gallons is the same 1 in thread one size up.

Skip it if the pump is rated above 5 GPM: Amtrol’s table moves 10 GPM to the WX-203 or WX-250.

Amtrol Well-X-Trol WX-203: buy it or skip it?

Buy it if the pump is 10 GPM, up to 3/4 hp, on a 30/50 switch: that is the exact cell in Amtrol’s quick-sizing table. The spec card prints 32.0 gallons, 9.9 gallons of drawdown at 30/50 and 8.6 at 40/60, a 1 in NPTF connection and 150 psig.

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The flaw is height. The 32-gallon class stands taller than the 20-gallon class on the same 15 in footprint, and the cross-reference page carries Amtrol’s heights, so measure the clearance above the tank tee before ordering.

Skip it if the switch is 40/60 and the pump is 10 GPM: Amtrol’s table picks the WX-250 there, not the WX-203.

Amtrol Well-X-Trol WX-250: buy it or skip it?

Buy it if the pump is 10 GPM on a 40/60 switch, or a 5 GPM pump rated over 3/4 hp, which puts it on Amtrol’s 2 minute column. The spec card prints 44.0 gallons, 13.6 gallons of drawdown at 30/50 and 11.8 at 40/60, a 1 1/4 in NPTF connection, 22 in diameter by 36 in tall and 150 psig.

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The flaw is the thread: the step from the WX-203 to the WX-250 is also the step from 1 in to 1 1/4 in NPTF, so the existing tank tee may not fit. Amtrol’s card makes that break at the WX-205 and above.

Skip it if the pump is 20 GPM: the same table lists the WX-255 at 30/50 and 40/60 on a 1 minute run, and two WX-255 tanks on the 2 minute basis.

Amtrol Well-X-Trol WX-255D: buy it or skip it?

Buy it if the pump is 20 GPM, or any pump over 3/4 hp that Amtrol’s 2 minute column sends past the WX-250. The spec card prints 81.0 gallons for the WX-255, 25.0 gallons of drawdown at 30/50 and 21.7 at 40/60, 1 1/4 in NPTF and 150 psig; the D in the listing title is the DuraBase stand.

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The flaw is that 81 gallons of shell is a floor-space decision, and the 2 minute column for a 20 GPM pump calls for two of them.

Skip it if the pump is under 3/4 hp and 10 GPM or less: a WX-203 or WX-250 meets Amtrol’s 1 minute rule at a fraction of the footprint.

Pentair Wellmate WM-14: buy it or skip it?

Buy it if the tank lives in a damp crawl space or anywhere a steel shell rusts. Pentair’s WellMate table lists the WM-14WB at 47.1 gallons, 14.6 gallons of drawdown, 125 psi maximum operating pressure, a 1 1/4 in male NPT connection and 46.27 lb, in a corrosion-proof composite shell.

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The flaw is the missing column: Pentair prints that 14.6 gallons with no switch range beside it, so it cannot sit against Amtrol’s 40/60 figures on equal terms, and the page prints no pre-charge and no warranty length.

Skip it if you want the pre-charge rule from the maker’s own document: on this page that rule comes from Amtrol, Goulds, State and Pentair’s steel line, not from the WellMate page.

Who should skip every tank on this page?

Anyone whose old tank still holds air. Drain it, read the Schrader valve, compare with cut-in minus 2 psi. If the charge is there, the tank is not the part to buy, and the well pump not working guide covers the rest of the system.

Anyone on city water looking for a thermal expansion tank. That is a different device sized from the water heater, and the expansion tank size calculator does that arithmetic.

Anyone with sand in the water. A new tank fills with the same sediment as the old one, so the whole-house sediment filter review goes ahead of it in the line.

What goes wrong?

The pre-charge never gets set. Every Amtrol ships at 38 psig and Goulds and State at 38 psi; on a 30/50 switch that is 10 psi high, and Amtrol’s manual requires the tank drained before any adjustment.

The thread does not match the tank tee. Amtrol’s card breaks from 1 in to 1 1/4 in NPTF at the WX-205; Water Worker breaks at the HT-44B, per the cross-reference page.

The tank freezes. A pressure tank in an unheated pump house is on the well winter freeze checklist, with the pipe that feeds it.

Frequently asked questions

Sources

1. Amtrol, Well-X-Trol Next Generation Well Tanks spec card MC7025 (03/24): model table WX-101 to WX-350, tank volume, drawdown at 30/50, 40/60 and 50/70 psig, connection size, 150 psig maximum working pressure, 38 psig factory pre-charge, ESP quick-sizing table by pump GPM for pumps up to 3/4 hp (1 minute run) and over 3/4 hp (2 minute run) (manufacturer or vendor document)
2. Amtrol, Well-X-Trol Installation & Operation Instructions 9016-868 MC10185: set pre-charge 2 psig below pump cut-in (38 psig example for 40/60), drain the tank before adjusting, 150 psig maximum working pressure, diaphragm well tank description, 7-year limited warranty on WX models, warning against adjusting pre-charge on a tank with diminished integrity (manufacturer or vendor document)
3. Water Worker, Well Tank Selection Guide: HT-series volume and drawdown at 20/40, 30/50 and 40/60, and the cross-reference chart by capacity class (retailer listing or retailer-hosted document)
4. Pentair, PRO-SOURCE Steel Pressurized Tanks data sheet M9134WS: one gallon of drawdown per gallon per minute at pump capacity, 40 PSI nitrogen-rich pre-charge, seamless one-piece PVC water cell, 100 PSI maximum operating pressure, drawdown table at 20-40, 30-50 and 40-60 (manufacturer or vendor document)
5. Goulds Water Technology, HYDRO-PRO Water System Tank technical brochure BHYDRO R7: V45 to V350 volume, drawdown at 20/40, 30/50 and 40/60, 38 PSI pre-charge, 1 in and 1 1/4 in NPTF connections, NSF Certified to NSF/ANSI 61-G (manufacturer or vendor document)
6. State Water Heaters, Residential Pump Tanks brochure SPMCA00107 (August 2023): SPMD and SSB diaphragm pump tanks, butyl parabolic diaphragm, 38 psi pre-charge, 100 psi (SPMD) and 125 psi (SSB) maximum working pressure, 5-year limited warranty, model volume and connection table (manufacturer or vendor document)
7. Reliance Water Heaters, PMD 20 100 20-Gallon Free-Standing Diaphragm Pump Tank: 20 gallon rated storage, 1 in connection, 100 psi maximum working pressure, parabolic diaphragm, 5-year limited warranty (manufacturer or vendor document)
8. Pentair, WellMate WM Series Tanks: WM-4 to WM-14WB capacity, drawdown (no pressure range printed), 125 psi maximum operating pressure, connection size, weight, composite construction (manufacturer or vendor document)
9. Water Well Journal, Tank Selection by the Numbers: minimum run time of one minute under 2 hp and two minutes at 2 hp and above, drawdown equals pump GPM times run time, fewer than 300 starts per 24 hours for motors under 1 HP (manufacturer or vendor document)