Why the numbers disagree
Bob Vila's well drilling guide lists a storage tank at 100 to 700 dollars. This Old House says a large pressure tank costs 1,400 to 2,400 dollars. Bob Vila's well pump guide puts a full pressure tank replacement at 800 to 3,800 dollars. These do not conflict once you notice what each one measures: a small tank, a large tank, and a tank with labor and related parts.
For a typical house on a well, the middle figure is the more useful one, because it includes labor and the related parts. A property that also waters a barn or irrigation tends to land toward the larger sizes.
| Figure | Source and year | What it likely covers |
|---|---|---|
| 100 to 700 dollars | Bob Vila, drilling guide | A storage tank as an add-on to a new well, equipment only |
| 800 to 3,800 dollars | Bob Vila, pump guide | Replacing a pressure tank, with the range reflecting size and labor |
| 1,400 to 2,400 dollars | This Old House, 2026 guide | A large pressure tank in a new-well package |
What the tank actually does
A pressure tank is a steel shell with air on one side and water on the other, usually separated by a rubber bladder. Penn State Extension describes the cycle: the pump fills the tank until pressure reaches about 40 psi, a switch shuts the pump off, and the tank pushes water out to the house until pressure falls to about 20 psi, when the pump starts again.
Only about a fifth of the tank holds usable water. A 42-gallon tank delivers roughly 8 gallons per cycle, according to the same source. That is why a bigger tank means fewer starts per day, and fewer starts mean less wear on the pump motor.
Tank problem or pump problem?
A tank can fail without any part leaking. The air side loses pressure, the bladder tears, and the tank fills with water until it can no longer cushion the pump. Pentair's tank manual warns that a lost air charge can lead to waterlogging and bladder failure. The usual symptom is a pump that starts and stops every few seconds.
Before you pay for a new tank, ask the provider to check the air charge with the power off and the tank drained. Pentair says to set the air pressure 2 psi below the switch's cut-in setting. Boshart, a tank supplier, says that margin is only the minimum for a 20-40 switch, and that a 40-60 switch wants about 6 psi. A tank that loses its charge again within weeks points to a torn bladder, and a tank that holds its charge but still cycles fast may simply be too small. If the shell is rusting through, replace it.
What changes the price
- Tank size, from a few dozen gallons up to a tank sized for a house with outbuildings
- Tank type, such as a bladder tank, a diaphragm tank or an older air-over-water tank
- Whether the pressure switch, gauge and fittings are replaced at the same time
- How much plumbing near the old tank has to be reworked to fit the new one
- Whether the pump is also near the end of its life, since doing both in one visit saves a second call-out
Sizing is a conversation, not a guess
Tell the provider everything the well supplies: house, barn, trough, irrigation. A tank that is too small makes the pump start often, and that wear shows up months later as a pump bill. Ask what size they propose and why, and whether a constant-pressure system, which Bob Vila prices at 2,000 to 5,000 dollars, would suit a property with uneven demand.
If the tank is in a pump house, ask about floor space and access too, since a bigger tank has to physically fit and be reachable. Compare quotes line by line, as in the well drilling cost guide, and see the pressure tank and well system service page for what a visit includes.
Safe checks before you call
Look at the gauge when no water is running and look for rust or moisture at the base. Do not open the switch cover or touch wiring; well systems run on high-voltage power. The pump-not-working checklist shows which checks are safe and where to stop.
Common questions
Can I just add air to the tank myself?
Only with the power off and the tank fully drained, and only to the setting your tank and switch call for. The manufacturer's instructions apply. If air leaks out again, the tank needs a provider.
Does a bigger tank always help?
A larger tank means fewer pump starts, which is easier on the motor, but it costs more and needs the space. Size it to the demand.
Is the pressure switch part of this price?
It depends on the quote. We found no reliable published price for the switch alone, so ask for it as a separate line.