A typical well pump fills a pressure tank in 5 to 15 minutes, depending on your tank size and pump capacity
The time it takes your pump to fill the tank depends on three things: how large your pressure tank is, how much water your pump can deliver per minute, and how low the pressure has dropped before the pump kicks in. A 42-gallon tank with a 10-gallon-per-minute pump will fill faster than a 119-gallon tank with the same pump. If you notice your pump running much longer than 15 or 20 minutes to refill, or if it cycles on and off very frequently, something is usually wrong.
The pump should stop running once the pressure tank reaches its cut-off pressure—usually between 60 and 80 pounds per square inch (PSI), depending on how your system is set. If the pump keeps running past that point, or if it barely runs at all, the problem is often a failed check valve, a waterlogged tank, or a pressure switch that needs adjustment.
Key Takeaways
- A healthy well pump typically fills a standard pressure tank in 5 to 15 minutes before shutting off at the cut-off pressure.
- Pump runtime depends on tank size, pump flow rate, and the pressure drop between when the pump starts and stops.
- If your pump runs continuously for more than 20 minutes or cycles every few minutes, the check valve, pressure tank, or pressure switch likely needs attention.
- You can estimate your pump's flow rate by timing how long it takes to fill a 5-gallon bucket with a faucet supplied by the well.
- A waterlogged pressure tank—one with no air cushion—forces the pump to run longer and cycle more often than normal.
What happens inside the pressure tank during a pump cycle
Your pressure tank holds both water and compressed air. The air acts as a cushion that keeps pressure steady as you use water throughout the house. When you turn on a faucet, water leaves the tank and pressure drops. Once pressure falls to a set point—usually around 40 PSI—the pressure switch signals the pump to start. The pump fills the tank with water, compressing the air inside, until pressure rises to the cut-off point (typically 60 PSI), at which point the switch shuts the pump off.
The time this takes is the runtime you observe. A pump that delivers 10 gallons per minute filling a 42-gallon tank will take roughly 4 to 5 minutes, assuming the tank starts at the low-pressure threshold. Larger tanks or slower pumps take longer. This is normal and expected.
How to measure your pump's flow rate
Knowing your pump's flow rate helps you understand whether the runtime you are seeing is reasonable. The simplest method is to time how long it takes to fill a 5-gallon bucket from a faucet supplied by the well when the pump is running and the tank is not actively refilling.
Turn on a cold-water faucet (not the one closest to the pressure tank if possible) and fill a 5-gallon bucket while timing it with a phone or watch. If it takes 30 seconds, your pump delivers 10 gallons per minute. If it takes 60 seconds, your pump delivers 5 gallons per minute. Once you know this rate, you can estimate how long a full tank refill should take by dividing the tank size by the flow rate. A 42-gallon tank with a 10-gallon-per-minute pump should fill in roughly 4 minutes; a 119-gallon tank with the same pump should take about 12 minutes.
Signs your pump is running too long or too often
If your pump runs for 20 minutes or longer to fill the tank, or if it turns on and off every few minutes even when you are not using water, one of three problems is usually at fault: a failed check valve, a waterlogged pressure tank, or a pressure switch that is set incorrectly or failing.
A check valve prevents water from flowing backward out of the tank into the well when the pump stops. If it fails, water leaks back into the well, and the pump must refill the tank from scratch each time it cycles. You will hear the pump start frequently even when no one is using water. The check valve is typically located on the discharge line between the pump and the tank.
A waterlogged pressure tank has lost its air cushion, usually because the air valve (called a Schrader valve, like a tire valve) has failed or because water has entered the air chamber. Without air, the tank cannot hold pressure, so the pump must run longer and cycle more often. You can check this by tapping the top of the tank—a healthy tank sounds hollow; a waterlogged one sounds full of water all the way up.
A pressure switch that is set too low or failing will cause the pump to run longer before shutting off, or to start cycling too frequently. This requires adjustment or replacement by someone familiar with well systems.
Normal runtime for common tank sizes
| Tank Size | Pump Flow Rate | Expected Fill Time |
|---|---|---|
| 42 gallons | 5 GPM | 8–10 minutes |
| 42 gallons | 10 GPM | 4–5 minutes |
| 82 gallons | 5 GPM | 16–18 minutes |
| 82 gallons | 10 GPM | 8–10 minutes |
| 119 gallons | 5 GPM | 23–25 minutes |
| 119 gallons | 10 GPM | 11–13 minutes |
These times assume the tank starts at the pump-on pressure (usually 40 PSI) and fills to the pump-off pressure (usually 60 PSI). Actual times vary slightly based on your system's exact settings and how much water is already in the tank. If your runtime is significantly longer than these ranges, investigate the check valve, tank condition, and pressure switch.
When to call a well service professional
If your pump runs longer than 20 to 25 minutes to fill the tank, or if it cycles on and off every few minutes without anyone using water, do not wait. Continuous or frequent cycling wears out the pump motor and pressure switch faster and can indicate a serious leak or component failure.
A well service technician can test the check valve, measure the air pressure inside the tank, inspect the pressure switch, and check for leaks in the supply line. They can also verify that your pump is delivering the flow rate it should. If the tank is waterlogged, it usually needs to be replaced or drained and re-pressurized. If the check valve has failed, it must be replaced. These are not repairs most homeowners can safely perform without specialized tools and knowledge of well system pressure.
Frequently Asked Questions
Is it normal for the pump to run every time I use water?
No. The pump should run once to refill the tank after you use water, then stay off until pressure drops again. If it turns on every time you use a faucet, even briefly, the check valve has likely failed or the tank is waterlogged. Call a well service professional to diagnose which.
What if my pump runs for 30 minutes straight?
This indicates a serious problem—either the pump cannot reach cut-off pressure because of a leak or failed check valve, or the pressure switch is not working. Do not ignore this. Continuous running will burn out the pump motor. Turn off the pump at the breaker and call a well service technician.
Can I adjust the pressure switch myself to make the pump stop sooner?
Pressure switches have adjustment screws, but changing them without understanding your system can damage the pump or leave you without water pressure. If you believe the switch is set incorrectly, have a professional verify the settings and make adjustments. They can also test whether the switch itself is failing.
How do I know if my pressure tank has lost its air?
Tap the top of the tank with your knuckles. A healthy tank sounds hollow and resonant. A waterlogged tank sounds dull and full. You can also watch the pump cycle—if it turns on and off very frequently (every few minutes) even when you are not using water, the tank has likely lost its air cushion.
Does a larger pressure tank mean the pump runs longer?
Yes, because a larger tank holds more water. However, a larger tank also means the pump cycles less often, which is easier on the motor and pressure switch. The trade-off is that each individual fill cycle takes longer, but the system runs less frequently overall.