How Sump Pumps Work

Sump Pump Maintenance

Rex Hipes checks on the sump pump in the basement of the Clarksville Christian church while fighting rising waters from the Mississippi River.
Rex Hipes checks on the sump pump in the basement of the Clarksville Christian church while fighting rising waters from the Mississippi River.
Photo by Joe Raedle/Getty Images

­Most sump pumps are equipped with water level or flood alarms, usually battery powered, that alert you if the pump isn't working properly and water is backing up. More sophisticated systems can notify your alarm company or call your cell phone if the water starts to rise. Fortunately, this shouldn't happen often. Sump pumps on the whole are quite reliable. But as with any other important piece of equipment, regular maintenance is always a good idea. Spend a few minutes every couple of months, when heavy rains are forecast and in early spring to ensure reliable sump pump operation. Basic sump pump maintenance is usually as simple as doing these few jobs.

  • Make sure the pump is plugged in to a working ground fault circuit interrupter (GFCI) outlet and the cord is in good shape. In damp areas, GFCI ­breakers may trip, effectively shutting off the sump pump. Check in on your sump pump periodically so you can reset the GFCI if necessary.
  • Ensure the pump itself is standing upright. Vibrations during operation can cause it to fall or tilt onto one side. This can jam the float arm so it can't activate the pump.
  • Periodically pour a bucket of water into the pit to make sure the pump starts automatically and the water drains quickly once the pump is on. If the pump doesn't start, have it serviced.
  • Physically remove a submersible pump from the pit and clean the grate on the bottom. The sucking action of the pump can pull small stones into the grate, blocking the inlet or damaging the pump over time.
  • Ensure the outlet pipes are tightly joined together and draining out at least 20 feet (6 meters) away from your foundation.
  • Make sure the vent hole in the discharge pipe is clear.

Another important point is the sump pump's power supply. The fact that sump pumps rely on electricity to operate does make them vulnerable in the event of a power outage. Fortunately, there are backup options available. For some people, at least those on municipal water systems -- and assuming the city water system is still functional -- water-powered sump pumps that don't need any electricity are an option. These pumps literally use the pressure of flowing water to pump water out of the sump. The downside to this design is that the pumping process uses virtually the same amount of city water as the quantity of water it pumps out. So, while water-powered pumps aren't necessarily a good choice for a main pump, they offer a viable option for a short duration backup pump.

Sump pumps with backup battery power are also commonly available. The backup power comes from a car battery -- or even better, a deep cycle boat battery. Most of the systems charge the batteries while the power is on, ensuring the battery is fully charged in the event of a power outage. Alternatively, a trickle charger used for car batteries is also an option.

Some homeowners use backup gasoline or diesel generators to provide their own electricity in the event of a power outage. Since a small sump pump needs 800 to 100 watts to operate and can draw up to 1,800 watts when starting, a backup generator needs to be sized properly and, of course, well maintained.

If all else fails, you can turn to a hand-operated bilge pump or a bucket brigade to move water out of the pit during a power outage.

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More Great Links


  • Friedman, Daniel. "Buying, Installation and Maintenance Guide for Sump Pumps." ­
  • Grand Forks Herald. "Sump pumps causing slippery Grand Forks streets, sidewalks." 11/21/2008.­
  • Henkenius, Merle. "Installing a Sump Pump." Popular Mechanics. 1/1997.
  • Sump Pump Information