Low Water Pressure From a Well

Read the gauge first

Open a tap and watch the gauge on the tank tee. Note the pressure when the pump starts (cut-in) and when it stops (cut-out). Most switches are set at 30/50 or 40/60 psi.

What you see narrows it down:

• Gauge swings normally, but pressure feels weak at the low end. Your switch setting is just low, or the water stops before the pump kicks on. See the first two causes below.
• Gauge stays high, but taps are weak. The pressure is there at the tank and getting lost on the way, usually in a filter.
• Needle flutters and the pump clicks on and off. That's the tank.
• Pump runs and the gauge climbs slowly or stalls. That's the pump or the well.

Likely causes

1. 1

   Cause 1: The switch is set low

   A 30/50 switch lets pressure fall to 30 psi before the pump starts, and you'll feel that dip in the shower. That's normal, not a fault. If it bothers you, the range nut on most switches raises the cut-in and cut-out together by the same amount. Raising a 30/50 by 10 psi gives you roughly 40/60. Reset the tank's air charge below the new cut-in. Our pressure switch adjustment guide has the steps.

   Don't raise it past what your pump can reach, or it'll run and never shut off.

2. 2

   Cause 2: Water stops before the pump starts

   If the flow nearly dies for a second before the pump kicks in, the tank's air charge is too close to the cut-in pressure. Boshart explains that with too little gap, the tank empties before the pump starts. It often shows up in spring, because warmer air in the tank raises the pre-charge.

   Boshart's fix is to set the pre-charge about 15% below cut-in to allow for gauge error and temperature swings. That's about 6 psi below cut-in on a 40/60 switch. Drain the tank to zero before you check it.

3. 3

   Cause 3: A clogged sediment filter

   This is the one people forget. A whole-house sediment filter after the tank slowly plugs, and pressure at the taps drops while the tank gauge reads fine. Boshart notes that sand in the water can clog sediment filters before their normal 4 to 6 month change interval. Swap the cartridge and test again. If filters clog fast, the well is pumping sand, which is a bigger problem; see whole house water filters for well water.

4. 4

   Cause 4: A waterlogged pressure tank

   When the tank loses its air, pressure pulses up and down. Boshart lists rapid switch clicking, short cycling, a fluttering gauge and pulsing water pressure as the signs. Knock on the top half of the tank: it should sound hollow. If it sounds solid, recharge it or replace it. More on waterlogged pressure tanks.

5. 5

   Cause 5: A worn pump

   Pumps lose capacity as they wear. Goulds lists excessive pump wear, debris binding the pump and lift too high for the pump among the causes of little or no water delivered. The sign is a gauge that climbs slower than it used to and a pump that runs longer each cycle. HomeGuide lists decreasing water pressure as one of the main signs a well pump is going bad.

   On switches with a low-pressure cutoff lever, a weak pump can also trip the cutoff. Boshart says some switches shut the pump off when pressure falls about 10 psi below cut-in, and a pump with worn or clogged impellers that can't keep up will trip it even though the switch is fine. See low-pressure cutoff switches.

6. 6

   Cause 6: The well can't keep up

   If pressure is fine in the morning and falls off during long showers, laundry or watering, the water level may be dropping to the pump. Goulds says to check the well's recovery and lower the pump if possible when it isn't fully submerged. Spitting faucets along with the low pressure point here too. See well yield and recovery rate.

7. 7

   Cause 7: Clogged switch tube, scaled pipes or a leak

   The small nipple feeding the pressure switch can plug with sediment, so the switch reacts late or not at all. Old galvanized pipe scales up inside until the house chokes on its own plumbing. And a leak anywhere lowers pressure while making the pump work harder. Close every fixture and watch the gauge; if it drops, find the leak.

Fixes

How to increase water pressure from a well

Once you've ruled out a fault, these are the real ways to get more pressure:

• Raise the switch setting by one step, usually 30/50 to 40/60, and reset the tank's air below the new cut-in. It's free, and often enough.
• Clean up the filter setup. Bigger housings or a spin-down filter ahead of the cartridge filter cut pressure loss.
• Install a constant pressure system. A variable-speed drive holds one pressure instead of swinging between cut-in and cut-out. Franklin's SubDrive systems come with a pressure transducer or sensor; the sensor ships factory set to 50 psi. See constant pressure well pumps.
• Add a booster pump if the house is far uphill from the tank. HomeGuide prices a booster pump at $1,000 to $2,000 and up.

A bigger pump is usually not the answer. If the well can't supply more water, a bigger pump just runs it dry faster.

When to call a pro

Call a well contractor if the gauge stalls below cut-out, the pump runs much longer than it used to, the low-pressure cutoff keeps tripping, or you see sand. Those point to the pump or the well, and both mean someone has to pull the pump or measure the water level. HomeAdvisor puts the average well pump repair at $974.

If you were searching for an HVAC "low pressure switch" on an air conditioner, that's a refrigerant safety switch and a different job for an HVAC technician.