What limits water pressure in a well system

Well water pressure depends on three things: how deep the water sits below the surface, how much water the pump can move per minute, and whether the pressure tank is working correctly. If your pressure is low, one of these three is the problem. Most homeowners can fix the tank or the pump settings themselves. If the water table has dropped or the well is running dry during peak use, you need a professional assessment.

The pressure tank stores water under air pressure so your pump does not run constantly. Over time, the air charge inside the tank leaks out or gets absorbed into the water. When the air cushion disappears, the pump cycles on and off rapidly and pressure drops. This is the most common cause of low pressure and the easiest to fix.

Key Takeaways

  • A waterlogged pressure tank — one that has lost its air charge — is the most common reason for low well pressure and can be fixed by draining and recharging the tank yourself.
  • Your pump's pressure switch controls when the pump turns on and off; adjusting it upward can increase pressure, but the switch has a maximum setting based on your pump model.
  • If the well itself is producing less water than it used to, the water table may have dropped or sediment may be clogging the intake; a well contractor can test the flow rate and diagnose the cause.
  • Increasing pressure beyond what your plumbing and fixtures are rated for can damage pipes, water heaters, and appliances, so check your system's limits before making changes.

Recharge the pressure tank

Start here. Turn off the pump at the breaker. Open a faucet at the lowest point in your house to drain the system completely — this usually takes five to ten minutes. Close the faucet when water stops flowing.

Locate the air valve on top of the pressure tank. It looks like a tire valve. Use a tire pressure gauge to check the current air pressure inside the tank. The air pressure should be about 2 pounds per square inch (PSI) below your pump's cut-in pressure — the pressure at which the pump turns on. If your pump is set to cut in at 40 PSI, the tank air pressure should be around 38 PSI. If the gauge reads zero or very low, the tank has lost its charge.

Use an air compressor to add air through the valve until you reach the correct pressure. Do not overcharge; too much air pressure will cause the pump to short-cycle and wear out faster. Turn the pump back on at the breaker. Open a faucet and let water run for a minute to refill the tank, then check your pressure at another faucet. Pressure should now be stable.

Adjust the pressure switch

The pressure switch sits on a pipe near the pressure tank and has two bolts on top. One bolt controls the cut-in pressure (when the pump starts), and one controls the cut-out pressure (when the pump stops). The difference between them is usually 20 PSI — if cut-in is 40 PSI, cut-out is 60 PSI.

To increase pressure, turn the larger bolt clockwise in quarter-turn increments. Each quarter turn raises pressure by roughly 2 PSI. After each adjustment, turn the pump off at the breaker, open a faucet to drain the tank slightly, turn the pump back on, and measure the new pressure at a faucet. Stop when you reach your target pressure.

Do not exceed the maximum pressure rating for your pump — this is printed on the pump nameplate, usually between 60 and 80 PSI. Pushing beyond that voids the warranty and can damage the pump. Also check your home's plumbing code or your water heater manual; many systems are rated for 80 PSI maximum, and exceeding that can rupture pipes or damage appliances.

Check the pump intake and well depth

If recharging the tank and adjusting the switch do not help, the problem may be the well itself. A well contractor can perform a flow test to measure how many gallons per minute your well produces. If the flow rate has dropped significantly from when the well was new, sediment may be clogging the intake screen, or the water table may have fallen.

Sediment buildup can sometimes be cleared by shock chlorination — a process where a contractor flushes bleach through the well to kill bacteria and loosen deposits. This costs between $300 and $800 and works best if the problem is recent. If the water table has dropped permanently, you may need a deeper well or a larger storage tank to meet your household demand during peak hours.

Ask the contractor for the well's static water level (the depth of water when the pump is off) and the drawdown (how far the water level drops when the pump is running). If drawdown is severe — the water level drops more than 10 feet when you run multiple faucets — the well cannot keep up with your demand, and pressure will always be low during heavy use.

Install a larger pressure tank

If your well produces adequate flow but pressure still drops when you use multiple faucets at once, your pressure tank may be too small. A tank that is too small cannot store enough water to meet demand between pump cycles, so pressure falls quickly.

Tank size is measured in gallons. A household of four typically needs a 42-gallon tank; larger households or those with high-demand fixtures like hot tubs may need 60 gallons or more. A larger tank costs $400 to $800 installed and gives the pump more time to refill the tank, so pressure stays more stable during use.

Before buying a new tank, have a contractor measure your current tank and confirm it is properly charged. Many homeowners replace a tank unnecessarily when the real problem is a waterlogged existing tank.

Upgrade the pump if flow is too low

If the well produces water but the pump cannot move it fast enough, upgrading to a higher-capacity pump may help. Pump capacity is measured in gallons per minute (GPM). A typical household pump moves 10 to 15 GPM; larger homes or those with multiple bathrooms may need 20 GPM or more.

A new pump costs $800 to $2,000 installed, depending on the well depth and pump type. Submersible pumps (which sit inside the well) are more common in residential wells and are usually cheaper to replace than jet pumps (which sit above ground). Before replacing the pump, confirm with a contractor that the well itself can sustain higher flow. If the well cannot produce more than 5 GPM, a bigger pump will not help — the well is the limiting factor.

Know when to call a professional

Call a well contractor if recharging the tank and adjusting the pressure switch do not restore pressure within a week. Also call if you hear the pump cycling on and off more than three times per minute, if water is discolored or smells like rotten eggs, or if the pump is more than 15 years old and pressure has declined gradually over time.

A contractor can test the well's flow rate, measure water level, check for sediment or bacterial growth, and determine whether the problem is the pump, the tank, or the well itself. This diagnostic visit usually costs $150 to $300 and will tell you whether a straightforward fix like tank recharge will work or whether you need a larger investment.

Frequently Asked Questions

Can I increase water pressure without adjusting the pressure switch?

Yes. Recharging the pressure tank alone often restores pressure to normal. If the tank is properly charged and pressure is still low, then adjust the switch. Most low-pressure problems are solved by the tank, not the switch.

What happens if I set the pressure switch too high?

The pump will cycle on and off rapidly, wearing out the motor faster and shortening the pump's life. You may also damage pipes or appliances rated for lower pressure. Stay within your pump's maximum rating and your home's plumbing code limits.

How often should I recharge the pressure tank?

A properly functioning tank should hold its air charge for years. If you need to recharge more than once per year, the tank's internal bladder may be failing and the tank should be replaced.

Will a bigger tank solve low pressure?

Only if the well produces adequate flow but the tank is too small to store enough water between pump cycles. If the well itself is slow, a bigger tank will not help — the pump still cannot move water fast enough to meet demand.

What is normal water pressure for a well?

Most well systems are set to cut in at 40 PSI and cut out at 60 PSI. Some systems run at 50/70 PSI. Check your pressure switch settings or your well contractor's paperwork to see what your system is designed for.