Quick answer: a failed pressure tank is often a $300 to $800 job according to a published North Carolina cost guide. It is worth fixing promptly because a bad tank forces the pump to cycle constantly, and short cycling is one of the main ways pumps die early. No county permit is needed to replace a tank.
What the pressure tank does
A well pump is not meant to start every time you open a faucet. The pressure tank stores a small reserve of water under pressure, so the pump runs in longer, less frequent cycles. Most modern tanks have a rubber bladder or diaphragm that separates the water from a cushion of compressed air. When the bladder tears, the air leaks out, or the tank rusts through, the cushion is gone and the pump has to cycle for every small draw.
Signs the tank is the problem
- Rapid cycling. The pump clicks on and off every few seconds when you run a little water.
- A bouncing pressure gauge. Pressure rises and falls fast instead of moving smoothly.
- Surging pressure. The shower alternates between strong and weak.
- A heavy, solid-sounding tank. Tap the side of the tank. A healthy tank sounds hollow near the top where the air is. If it sounds solid all the way up, it may be waterlogged.
- Water at the air valve. If water comes out of the small valve on top when it is pressed, the bladder has failed. A contractor should check this, not you.
- Rust, corrosion, or a wet floor. A leaking or rusted shell is a replacement, not a repair.
Other problems can look similar, including a worn pressure switch, a leak in the plumbing, or a pump that is itself worn. A contractor will test before recommending a replacement. If you are not sure, read about well pump repair.
What a replacement involves
- The contractor turns off power and drains the old tank.
- The old tank is disconnected and removed. Unions, valves, and the pressure gauge are inspected and replaced if needed.
- The new tank is installed and its air charge is set before water is added.
- The pressure switch is checked against the new tank. A worn switch is often replaced at the same time.
- The system is refilled, purged of air, and tested for cycling and leaks.
Many replacements take a couple of hours. Where the tank is located matters: a tank in a cramped crawlspace or on a lower level of a hillside house can slow the job.
Air charge: the 2 pound rule
A tank's air charge should be set about 2 pounds per square inch below the pressure at which the pump switches on, which is called the cut-in pressure. The Michigan state water well manual states this directly, and state agencies in Alaska and Illinois publish the same guidance. A tank with too little air cannot cushion pump starts, and a tank with too much air stores less water. Checking the charge requires power off and the tank empty of water, which is why it is best left to a contractor.
Sizing a replacement tank
Most homes use a tank in the 20 to 50 gallon range. A larger tank gives the pump longer rest between cycles and can extend pump life. A published North Carolina cost guide notes that if a contractor recommends a bigger tank during a pump replacement, it is usually worth it. The right size depends on pump flow, household size, and the well's yield. In low-yield Blue Ridge wells, where U.S. Geological Survey studies report average yields of roughly 1 to 20 gallons per minute, a larger tank can also help smooth demand on the well.
| Tank size | Installed range |
|---|---|
| Small, 20 to 30 gallons | $150 to $350 |
| Standard, 30 to 50 gallons | $300 to $600 |
| Large, 80 gallons or more | $500 to $800 or more |
| Replaced while the pump is out of the well | Add roughly $400 to $1,200 |
Replace the tank with the pump?
If your pump is old and the tank is also showing signs of age, doing both at once saves a second visit. A Piedmont Triad contractor's published guide says replacing a pump and tank together typically runs $2,000 to $4,200 combined, and that the tank is cheapest to do while the well is already open. If the pump is not near the end of its life, a stand-alone tank swap can stop the damage before it starts.
Wiring from the well pump to the pressure switch is part of this work. North Carolina law allows certified well contractors to run that wiring, and it allows them to run the water pipe from the well to the tank. If the project involves new electrical service, a licensed electrician may also be needed.
After Helene, think about the tank too
Floodwater can reach pressure tanks, switches, and wiring in low-lying utility rooms and crawlspaces. If your system was wet, an electrician and a well contractor should look at the electrical parts before the system is turned on. For wells that were flooded, the North Carolina Department of Health and Human Services also recommends disinfecting and testing the water. Read more on the service area pages.
Next steps
If you have water but the pressure is wrong, a tank problem is a strong candidate. If you have no water at all, start with no water from your well. To see how a tank fits into a bigger budget, check the well pump replacement cost guide. We route tank and pump requests across Buncombe County, Henderson County, and Madison County.
Frequently asked questions
How much does a well pressure tank replacement cost?
A published North Carolina cost guide lists pressure tank replacement at about $300 to $800 installed, with small 20 to 30 gallon tanks at $150 to $350 and large 80 gallon or bigger tanks at $500 to $800 or more. A contractor in the Piedmont Triad lists $400 to $1,200 when a tank is replaced while the pump is out. These are estimates, not quotes.
How long does a well pressure tank last?
Bladder style tanks commonly last many years, but the air charge and the bladder can fail sooner, especially if the pump cycles too often. If the tank is waterlogged, the pump starts and stops more frequently, which shortens pump life as well.
What are the signs of a bad well pressure tank?
The pump clicks on and off every few seconds, pressure swings from strong to weak, the pressure gauge bounces, or the tank feels full and heavy when you tap it. Water spurting from faucets with air is a different problem that can involve the well or a leak.
Can I recharge the air in the tank myself?
Adjusting a tank's air charge means shutting off power and draining the tank, and a mistake can damage the bladder or leave the pump running dry. Many homeowners leave it to a contractor. State well manuals say the charge should be set about 2 pounds per square inch below the pressure at which the pump turns on.
Do I need a permit to replace a pressure tank in North Carolina?
No. North Carolina law says a well repair permit is not required for repair work that involves only the repair or replacement of a pump or tank.