Understanding the Different Sump Pump Parts

If you own a home or other building prone to flooding, having a basic understanding of sump pump parts is good general knowledge. It may come in handy if ever you need to make a repair or replace a part. A sump pump is a relatively small contraption that usually is no higher than 3 feet. Installed in the lowest area of a basement or in ground-level crawlspace, a sump pump works to keep the ground dry and to prevent flooding by pumping water out of the space and away from the foundation so it can drain. There are two basic types of sump pumps: submersible and pedestal models. Submersible sump pumps are designed to sit in water, while pedestal pumps stay above it.

Sump Pump Parts

Not every important feature of a sump pump is a part of the pump itself. One of the most important is actually the hole or pit in which the pump sits. Familiarize yourself with these different parts of a sump pump in order to better understand how the device functions.

Sump Pit

This is a gravel-filled hole about a foot and a half wide and 2 feet deep in which the pump housing rests. The sump pit should be located in the lowest point of a basement so all gathering water flows directly to it. Once water drains into the sump pit, the pump begins to work to remove it.

Float Activator Arm

Much like the floating bladder found in a toilet tank, the float activator arm is a rubber, bell-shaped buoy that floats atop water inside the pump housing. Its arm is attached to the pump motor. As the water level rises, the float activates the pump motor, which, in turn, activates the pump.

Pressure Sensor

An alternative to a float activator arm is a pressure sensor. Since water applies more pressure than air, this part triggers the pump when it senses an increase in pressure.


Also called a centrifugal pump, the impeller is connected to the pump motor. It is a fan-shaped rotary part that uses centrifugal or outward-seeking force to move water in the housing away from it and up the discharge pipe. As it spins, water is pushed up the pipe to drain elsewhere. The motor will continue to turn the impeller as long as the float activator arm or pressure sensor detects the presence of water in the sump pit.

Discharge Pipe

This part is a basic drain pipe. It extends vertically out from the sump pump housing. Once it rises above ground level, the pipe makes a 90-degree turn with the help of an elbow joint. From there, the pipe continues horizontally away from the basement and foundation and discharges the water at a safe distance from the structure so it may drain.

Check Valve

This is a small 1-way valve located in the discharge pipe close to the pump. The check valve is necessary in order to prevent water from flowing back into the sump pit.

Besides the pump housing, which is basically a capped, cylindrical shaft with corrugated sides to let water seap in, these are the primary components of a sump pump.