My pump tank has a leak in it, and so needs to be replaced. The current tank is a 36 gallon tank, similar to this one. Is there any risk in upgrading to a 52 gallon tank, such as this one? I would think the benefit would be that the pump would have to run less often, but I'd like to have clarification on that too.

  • The only possible danger I can think of is the volume of water pumped in a single cycle. If your current tank pulls in say 10 Gal/ Cycle, and the new tank pulls in 15 Gal/Cycle, and your well flows at 12 Gal/(some time), it's theoretically possible that you could end up sucking air. Not likely, and a lot would have to go wrong, but it is theoretically possible. It has to do with how long it takes the well to get back to "full" after a cycle. Jun 20, 2012 at 21:33
  • @ChrisCudmore Good point, though it's slightly more complicated (of course). The well itself has a capacity, which depends largely on the depth, and so long as you don't use up that capacity before it recovers you're okay. As you point out though, if you use up the capacity in a single cycle you'll have a problem, but if you're doing that you're using more water than the well can handle anyway and should at the least have low-level protection (eg a low-pressure shut-off switch, or a controller like a Pumptec), and could possibly consider an entire low-yield system (involves a large cistern).
    – gregmac
    Jun 21, 2012 at 5:05

2 Answers 2


A larger tank will cause the cycles to be longer (slower), but overall the runtime will be the same (if you use 500 gallons of water, the pump has to supply 500 gallons of water). For example, if the tank is full and you open a tap, with a 36 gallon tank it may take 60 seconds before the pump starts, and then 30 seconds to run, and repeat. With a 55 gallon, it may take 90 seconds before the pump starts, and then it will run for ~50 seconds. In both cases, this is ~33% duty cycle (if you excuse my rounding errors for simplification), and so if you leave the tap open for 10 minutes you'll get a total of 198 seconds or 3.3 minutes of runtime.

The downsides to a larger tank are simply that it costs more and takes up more space.

The only real problem is if you have too small of a tank you'll cause the pump to cycle too quickly which wears it out faster.

  • The takes up more space may not be accurate if an old school tank, many of today's pressure tanks with a 100% bladder are 1/2 the size of old diphram tanks, I usually choose to get as big a tank that the space the original tank used. This will save $ as a 3x to 8× starting current is required reduce the starts and the power bill is reduced because the pump is running at FLA at a higher % and not starting more often cuts the over all power consumption.
    – Ed Beal
    Jul 8, 2018 at 19:53

Your well-pump should be sized to match the "make-up" (the speed at which water flows back into the well). That being said, bigger is better for your pressure tank. What kills well-pumps is starting, it takes the most abuse from starting, so running is the least work. So to have a larger tank means fewer starts and longer run times, and it also means more available volume and stable pressure in the water plumbing.

So short answer is there wouldn't be any risk as long as your pump is sized to the make-up of the well.

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