Grinder Pump Running Constantly? What It Means and What to Do

A grinder pump that runs constantly is not working the way it should. A healthy pump starts when the tank fills, empties it in a short cycle, and shuts off. If yours keeps running, the likely causes are a stuck float switch, a check valve that is stuck or leaking, a blocked discharge line, a leaking fixture feeding the tank, or a worn pump. Cut back on water use right away and call a technician, because a pump that never rests can overheat and burn out.

What does a normal grinder pump cycle look like?

When you run a load of laundry or a long shower, you may hear the pump start, run for a short time, and stop. Most of the day it sits quiet. If your pump runs for a long stretch with no water in use, or starts again and again, something is off.

Why would a grinder pump keep running?

Here are the most common causes we look for, from the simplest to the most serious:

• A leaking fixture. A running toilet or dripping faucet sends water to the tank all day, so the pump keeps cycling. This is the first thing to rule out.

• A stuck or failed float switch. The float tells the pump when to start and when to stop. If it is held up or fails, the pump may never get the signal to shut off.

• A check valve problem. The check valve keeps pumped wastewater from flowing back into the tank. If it sticks open or leaks, the same water returns and the pump has to move it again.

• A blocked or restricted discharge line. The pump runs, but it cannot push the water out the way it should.

• Water getting into the tank. In some systems, groundwater or surface water can leak in and keep the level up.

• A worn pump. Worn bearings, a damaged impeller or a weak motor can make a pump run long and loud without keeping up.

What can I safely check?

• Walk through the house and listen for a toilet that is running or a faucet that is dripping. Fix or shut off what you find.

• Look at the control panel, if you have one. Note any alarm light or horn. You can silence the horn with the button on the panel, but do not leave the power off.

• Hold off on laundry, the dishwasher and long showers until the pump is checked.

What should I never do?

• Do not open the tank lid and reach in. Sewage gas and moving equipment are dangerous.

• Do not hit or shake the discharge pipe, flip the breaker over and over, or pour chemicals into the tank.

• Do not wait a few days and hope it settles down. A pump that runs nonstop can overheat, and it can wear out much sooner.

When should I call?

Call right away if the pump keeps running after you've checked your fixtures, if an alarm is sounding, if you see water or smell sewage near the tank, or if the pump makes grinding or rattling noises. If the alarm is the main problem, see our grinder pump alarm repair page.

We work on grinder pumps for homes in Lago Vista, Jonestown and around Lake Travis. You can reach us at (512) 662-2949, Monday through Friday from 7:30 a.m. to 8 p.m. and Saturday from 8 a.m. to noon. A service visit starts with a $65 trip charge, and it is credited toward the work if you go ahead with the repair. We find the cause, explain it in plain words, and give you the options before anything starts.

To learn how your system works, read our grinder pump guide for Lago Vista homeowners, or see our grinder pump service page. A yearly visit through Real Home Care is a good way to catch float and valve problems early.

Frequently Asked Questions

Is it okay to leave a grinder pump running overnight?

Not if it never stops. Cut back on water use and call us. Long run times can overheat the motor and shorten its life.

Why does my grinder pump run when nobody is home?

The usual causes are a leaking fixture, a check valve letting water flow back into the tank, or a float that is not shutting the pump off.

Can a running toilet make my grinder pump run all day?

Yes. Even a small constant leak sends water to the tank, and the pump keeps cycling to move it.

Is a grinder pump that won't stop running an emergency?

Treat it as urgent. If you also have an alarm, or you see water or smell sewage near the tank, call us right away.

What does a check valve do on a grinder pump?

It is a one-way valve that keeps pumped wastewater from flowing back into the tank after the pump shuts off.