Why your well pump pressure drops and what you can do about it
Low water pressure from a well pump usually comes from one of three places: the pressure tank has lost its air charge, the pump itself is wearing out, or sediment is clogging the system. You can fix the first two yourself. The third often needs a professional. Before you do anything, check your pressure gauge — it should read between 40 and 60 pounds per square inch (PSI) when the pump is at rest. If it reads lower, or if pressure drops suddenly, one of these problems is likely at work.
The good news is that the most common cause — a waterlogged pressure tank — is fixable in an afternoon with basic tools. The harder fixes involve replacing parts or calling a well contractor, but knowing which problem you have saves money either way.
Key Takeaways
- A pressure tank that has lost its air charge is the most common reason for low well pump pressure and can be fixed by recharging it with a bicycle pump or air compressor.
- You can check your pressure tank's air charge by tapping it with a hammer — a hollow sound means it needs air, a solid thud means it is waterlogged.
- If recharging the tank does not restore pressure, the pump itself may be failing or sediment may be blocking the system, both of which usually require a professional.
- Pressure switches can fail and prevent the pump from running at all, which you can test by listening for the pump motor and checking the switch terminals with a multimeter.
- Well water filters and screens clog over time and reduce pressure gradually — replacing them is a straightforward maintenance task that improves flow.
How to recharge a waterlogged pressure tank
A pressure tank holds both water and air. The air acts as a cushion that keeps pressure steady between pump cycles. Over time, the air charge leaks out or gets absorbed into the water, leaving the tank full of water instead of the proper air-to-water mix. When this happens, the pump runs constantly and pressure stays low.
To recharge the tank, first turn off the pump at the breaker or switch. Locate the air valve on top of the tank — it looks like a tire valve on a car. Use a tire pressure gauge to check the current air pressure. It should be about 2 PSI below your pump's cut-in pressure (usually 38 PSI if your gauge reads 40 to 60). If the gauge reads zero or very low, the tank needs air.
Attach a bicycle pump or air compressor to the valve and pump air in until the gauge reads the correct PSI. Do not overfill — too much air pressure can damage the tank. Once you have added air, turn the pump back on and check your water pressure at a faucet. Pressure should rise noticeably within a few minutes. If it does not, the tank may have a failed internal bladder and will need replacement.
Testing the pressure tank with a straightforward tap test
Before you buy an air compressor or pump, you can get a quick sense of whether the tank is waterlogged by using a hammer. Turn off the pump and let the system sit for a few minutes so the tank is at rest. Then tap different sections of the tank with a hammer — listen to the sound it makes.
A hollow, ringing sound means the tank still has air in it. A solid, dull thud means the tank is full of water and has lost its air charge. If you hear the hollow sound, the problem is likely elsewhere — check the pressure switch or pump motor. If you hear the thud, recharging the tank as described above should restore your pressure.
This test is not foolproof — a tank can sound hollow but still have a failed internal bladder — but it tells you whether to start with the air valve or move on to other parts of the system.
When the pump motor itself is failing
If you have recharged the pressure tank and pressure is still low, the pump may be wearing out. A failing pump loses its ability to move water at full force, even when it is running. You can tell the pump is running by listening for the motor — it should make a humming or buzzing sound when you turn on a faucet or when the pressure drops below the cut-in point.
If the motor is not running at all, the problem is likely the pressure switch or an electrical issue, not the pump itself. If the motor is running but pressure stays low, the pump impeller (the spinning part inside) may be damaged or worn. This requires replacing the pump, which is a job for a well contractor. A new pump costs between several hundred and several thousand dollars depending on the type and depth of your well, so get a quote before you commit.
Before you assume the pump is bad, also check that the pump intake screen is not clogged with sediment — see the next section.
Clearing sediment from the pump intake and system filters
Sand, silt, and sediment can build up in the pump intake screen or in any filters between the well and your house. When this happens, water flow slows and pressure drops gradually over weeks or months. If your pressure has been dropping slowly rather than dropping suddenly, sediment is a likely culprit.
The easiest place to start is any whole-house filter you have — usually a cartridge filter near where the well line enters your house. Turn off the pump, close the isolation valve on the filter housing, and unscrew the filter bowl. If the cartridge inside is brown, tan, or visibly dirty, replace it with a new one of the same size and micron rating. This alone often restores pressure.
If you do not have a filter, or if replacing it does not help, sediment may be in the pump intake screen at the bottom of the well. This requires pulling the pump out of the well, which is a job for a professional. They can clean or replace the screen and flush the system. Sediment problems are more common in older wells or wells in sandy areas.
Checking and replacing the pressure switch
The pressure switch tells the pump when to turn on and off. If the switch fails, the pump may not run at all, or it may run constantly without building pressure. A failed switch is one of the most common reasons for sudden pressure loss.
To test the switch, listen at the pump motor when you turn on a faucet. You should hear a click as the switch closes, followed by the motor humming. If you hear nothing, the switch may be stuck open. If the motor runs constantly and never stops, the switch may be stuck closed.
You can do a basic electrical test with a multimeter set to continuity mode. Turn off power to the pump. Locate the pressure switch — it is a small cylindrical or box-shaped device screwed onto the pressure tank or the pump line. Disconnect the wires and touch the multimeter probes to the switch terminals. The meter should beep or show continuity when you squeeze the switch lever. If it does not, the switch is bad and needs replacement. A new pressure switch costs $50 to $150 and takes about 30 minutes to install if you are comfortable with basic wiring.
When to call a well contractor
Call a professional if recharging the pressure tank does not restore pressure, if the pump motor is not running at all, or if pressure drops suddenly and you cannot find a clogged filter. Also call if you suspect sediment in the pump intake, if the pump is more than 10 years old and pressure has been dropping slowly, or if you need to replace the pump itself.
A well contractor can pull the pump, inspect the intake screen, test the motor, and replace parts as needed. They also have tools to flush sediment from the system and to test water quality. The visit usually costs $150 to $300 for diagnosis, plus the cost of any parts or repairs. Getting a second opinion is reasonable if the quote is high.
Frequently Asked Questions
How do I know if my pressure tank is bad or just needs air?
Tap the tank with a hammer. A hollow sound means it has air and probably just needs recharging. A solid thud means it is waterlogged. You can also check the air valve with a tire pressure gauge — zero or very low pressure confirms the tank needs air. If recharging does not fix the problem, the internal bladder has failed and the tank needs replacement.
Can low water pressure damage my pump?
No, but a pump running constantly because of low pressure will wear out faster. If the pressure switch is stuck or the tank is waterlogged, the pump may run without stopping, which shortens its life. Fixing the underlying problem — recharging the tank or replacing the switch — protects the pump.
What PSI should my well pump be set to?
Most residential well pumps are set to cut in at 40 PSI and cut out at 60 PSI, meaning the pump turns on when pressure drops to 40 and turns off when it reaches 60. Some systems use 30/50 or 50/70. Check your pressure gauge or the label on your pressure switch to see what your system is set to. Do not adjust the switch yourself unless you are experienced — incorrect settings can damage the pump.
Why does my water pressure drop when I use hot water?
Hot water heaters can reduce pressure if they are undersized or if sediment has built up inside them. The heater fills slowly, which feels like low pressure. Flush the heater by turning off power, closing the inlet valve, and opening the drain valve at the bottom. Let sediment drain for a few minutes, then close the drain and refill. If pressure is still low, the heater may need replacement.
How often should I recharge my pressure tank?
A healthy pressure tank should hold its air charge for years. If you are recharging it more than once a year, the tank is failing and needs replacement. Frequent recharging means the internal bladder is leaking or the tank is corroding. Replace it rather than keep adding air.