Parts of a Sump Pump – Basin, Float Switch, Check Valve

All 23 parts on the diagram

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Basin and piping 10

Sump basin (sump pit) The pit in the floor where the water collects.
Sump cover (basin cover) It keeps debris from falling into the basin.
Inlet pipe (drain pipe) Ground water drains into the basin through it.
Float switch Rising water lifts the float, and the switch starts the pump.
Discharge pipe It carries the pumped water up and away from the house.
Check valve A one-way valve: water in the pipe cannot run back down.
Air bleed hole (relief hole) A small hole that keeps trapped air from stopping the pump.
Power cord It brings electricity from the receptacle to the pump motor.
Piggyback plug The switch's plug; the pump's plug pushes into its back.
Receptacle (outlet) The wall socket that the pump plugs into.

Submersible pump 6

Handle The loop on top that the pump is lifted by.
Motor housing The sealed case that keeps water away from the motor.
Volute (scroll housing) The casing the impeller spins in; it guides water to the outlet.
Impeller It spins on the motor shaft and drives the water out.
Inlet screen (intake screen) Water enters the pump through these slots.
Pump discharge (pump outlet) The threaded outlet that the discharge pipe screws into.

Pedestal pump 7

Motor It sits above the basin, up out of the water.
Switch The float rod moves its lever to start and stop the motor.
Column (pump column) It holds the motor up; the shaft runs down inside it.
Float rod It joins the float to the switch lever.
Float rod guide Clamped to the column, it keeps the rod upright.
Float It rises and falls with the water in the basin.
Base (pump base) The pump end on the basin floor; the impeller is inside.

How this list was compiled: Every name checked on 2026-09-30, a name kept only where two independent sources use it. Wikipedia, Sump pump (https://en.wikipedia.org/wiki/Sump_pump), and the installation manuals of five unrelated pump makers and sellers, read as archive.org full text for their part names only: one maker's submersible, pedestal and sump and effluent pumps (https://archive.org/details/manualzilla-id-6294902, https://archive.org/details/manualzilla-id-6288804, https://archive.org/details/manualzilla-id-6308344); a second seller's submersible pump with a vertical float switch (https://archive.org/details/manualzilla-id-7037818); a third maker's submersible and pedestal pumps (https://archive.org/details/manualzilla-id-7326274, https://archive.org/details/manualzilla-id-6198043); a fourth maker's pedestal pump (https://archive.org/details/manualzilla-id-5937068); a fifth seller's submersible pump (https://archive.org/details/manualzilla-id-6350321). Two manuals from one company count as one source. Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; a schematic of no maker's product, nothing traced. Licence: own work

How it works

A sump pump stands in a basin set into the basement floor and sends the water that collects there outside. The three drawings show the basin and its piping, a submersible pump cut open, and a pedestal pump.

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From the basin to the wall

Ground water runs through the inlet pipe into the sump basin. As it rises it lifts the float, and the float switch starts the pump. The impeller drives the water out of the pump discharge and up the discharge pipe, past the air bleed hole and through the check valve, which keeps it from running back.

Submersible or pedestal

A submersible pump sits under the water with its motor sealed in a housing. A pedestal pump keeps its motor on a column above the basin; a float on a rod moves the switch.

Questions and answers

What are the main parts of a sump pump?

A basin in the floor with a cover, the pump, a float switch, a discharge pipe and a check valve. Inside the pump, a motor turns an impeller in a casing called the volute, and water enters through an inlet screen.

What does the float switch do on a sump pump?

It turns the pump on and off. Rising water lifts the float, the switch starts the motor, and when the water has been pumped down the float drops and the motor stops.

What is the check valve for?

It is a one-way valve in the discharge pipe. Water can flow away from the basin, but the water left in the pipe cannot fall back in when the pump stops.

What is the difference between a pedestal and a submersible sump pump?

A pedestal pump has its motor on top of a column, above the basin. A submersible pump sits in the water with its motor sealed in a housing, so the basin can be covered.