A water pump that won't shut off typically means it cannot reach its target shut-off pressure. Immediately turn off power to the pump at the breaker to prevent it from overheating and burning out.
If your water pump won’t shut off, it is usually trying to compensate for a leak, a clog, or a mechanical malfunction. To prevent the motor from overheating and burning out, take the following steps immediately:
Cause #1: Faulty Pressure Switch (Automatic Controller)
If the pressure switch fails, the pump loses its “stop” signal and keeps running indefinitely. This is the single most common source of water pump issues related to non-stop operation.
If your water pump is running while no water is being used, it usually means water is escaping your plumbing system, causing a drop in line pressure that forces the pump to turn on. This is commonly called "phantom cycling."
Resetting a water pump pressure switch usually involves manually overriding a low-pressure cutoff or clearing tripped contacts. To do this, locate the small lever on the side of the switch box, hold it up in the start position for 20–30 seconds until the pressure builds up, and then release it.
To reset a well water pump, cycle its dedicated circuit breaker off for 60 seconds and back on. If your system has a low-pressure cutoff, locate the pressure switch (gray box near the pressure tank), hold the side lever in the "start" position until pressure builds, then release.
To tell if your water pump pressure switch is bad, first shut off the power and remove the switch cover. Look for visibly burned, pitted, or corroded contact points, or blockages in the small pipe/nipple supplying water pressure to the switch. The following common issues also indicate a bad switch:
The first signs of water pump failure are typically a small puddle of bright-colored coolant (green, pink, or orange) under the front of your car, a high-pitched whining or grinding noise from the engine, or an engine temperature gauge reading slightly higher than normal.
Replacing a pressure switch typically costs between $150 and $300 in total, though the exact price depends on whether it is for a well pump, water heater, or HVAC system.
Detecting Early Signs of Pump Failure
No, your water pump should not run constantly. A continuously running pump wastes electricity, causes premature wear, and risks overheating and burning out the motor. Pumps are designed to cycle on and off, turning on only when water is in use or to refill a pressure tank.
Why Your Pump Runs But No Water Comes Out. There are several reasons why you might face this issue: Low Water Table: Over time, especially during droughts, the water table can drop, causing the pump to run dry. Air in the Pump: Air can sometimes get trapped in the pump, preventing water flow.
If your pressure switch is stuck open, it usually isn't a faulty switch itself, but rather the system's way of detecting a safety issue—like blocked venting or a weak motor. The switch acts as a safety measure and stays open when it fails to detect the proper pressure or vacuum.
A water pump that won't shut off typically means it cannot reach its target shut-off pressure. Immediately turn off power to the pump at the breaker to prevent it from overheating and burning out.
The average cost for a Water Pump Replacement is between $857 and $1,106. Labor costs are estimated between $358 and $525 while parts are priced between $499 and $581. This range does not include taxes and fees, and does not factor in your unique location. Related repairs may also be needed.
Even if you don't see a single drop on the floor, a small hidden leak in any faucet, fitting, or pipe prevents the pressure from stabilizing at the cut-out point set in the pressure switch. The result: the pump runs continuously to compensate for the constant loss.
The typical lifespan of a water pressure switch is 10 to 15 years. However, this can vary significantly depending on usage, water quality, and the frequency at which your pump turns on and off.
The "135-degree rule" in plumbing states that the total (aggregate) horizontal change in direction for a drainage pipe—specifically trap arms—cannot exceed 135 degrees between the P-trap and the vent. Exceeding 135 degrees (such as using three 45-degree bends or a 90 and two 45s) requires a cleanout because sharp turns hinder flow and cause clogs.
What are the signs of a faulty pressure switch?
To test a car's water pump, check for coolant circulation by turning on your cabin heater to maximum—if it blows consistently hot air, the pump is likely circulating. Next, with the engine off, inspect the pump’s weep hole for leaks, and wiggle the pulley to check for failing, loose bearings.
With a bad water pump, coolant cannot circulate, and the engine would quickly overheat, resulting in potential breakdowns and costly repairs.
When a pressure switch goes bad, it usually fails in one of two ways: staying permanently open (preventing the equipment from turning on) or getting stuck closed (forcing it to run constantly). Because pressure switches are critical safety and control mechanisms, failure leads to specific equipment malfunctions depending on where they are used.
Neither is universally "better"; the choice depends on your home’s plumbing and water needs. A 40/60 switch is ideal for multi-story homes and modern fixtures, delivering stronger pressure. A 30/50 switch is better for smaller, single-story homes and older plumbing, as it puts less stress on fragile pipes.
To adjust a pressure switch on a water pump, turn off the power, remove the switch cover, and locate the adjustment springs. Turn the main/center spring clockwise to raise both start/stop pressures, or adjust the smaller differential spring to change the shut-off pressure independently.