Angie's LIST Guide to
Sump pumps

The word “sump” refers to the lowest point, which in a house is the watery pit in the basement where the pump is placed. The water level you see in the sump well represents the groundwater level around your house. When the level rises to the point set by the sensor, the pump is activated and works until the level drops below the sensor line.

There are two types of sump pumps – pedestal and submersible. A pedestal pump sits on a pedestal outside of the water collection well with a sensor dropped into the water. The submersible sump pump is self-contained and is designed to float in the water pit. A submersible pump can be expected to last anywhere from five to 15 years, while pedestal models may last twice as long.

Sump pump water is ground water, so it should not be routed into sanitary sewers. However, many homes built as recently as the 1970s do just that. Not only is this wasteful – because it puts more water than necessary into your town's wastewater treatment plant – but it increases your risk of raw sewage backup into your home.

As your main drain ages, encroaching tree roots and other blockages gradually reduce the volume of water that can travel through the pipe at any given time. You may not notice this just flushing toilets or even running the washing machine, but a sump pump produces a much higher volume of water that rushes into your sewer in a constant flow that lasts as long as the pump's cycle of activity.

If the sewer drain can't handle that volume, there's nowhere else for the excess water to go except up out of your toilets and floor drains – and now the sump water has been mixed in with sewage.