The Sump Pump Switch – How a Sump Pump Works

Oct 27, 2011
Don’t replace that old float switch, upgrade and get a new system!

When answering the question “How does a sump pump work?” we need talk about the sump pump switch.

The sump pump switch turns the pump on and off.  The on-off cycling of the sump pump, via the sump pump switch, depends on the water level within the sump pump pit liner.

There are many types of sump pump switches available and most sump pumps you purchase are equipped with a sump pump switch.

Before you purchase a sump pump, you should learn whether or not the switch can be replaced, without replacing the entire sump pump. An integral sump pump switch that cannot be replaced independently from the sump pump can lead to more costly repairs if the sump pump switch fails. And they do fail, probably more often then people realize. Have your sump pump serviced annually to know the health of your pumping system. 

Lets take a look at the various types of sump pump switches available. All these sump pump switches rely on the water level rising to activate the switch.


Sump Pump Tethered Float

The tethered float sump pump switch will float upwards as the water level rises causing an assembly within the float to turn the switch on. When the water level drops the assembly moves away from the switch turning the pump off.

The most common problem with these switches is that the float gets blocked preventing the pump from turning on.




Sump Pump Vertical Float – Independent


The independent vertical float switch manufactured by Glentronics has two small floats in a protective cage. The cage protects against blockage and the two floats provide back up against failure.

This particular switch is also equipped with a control box and an alarm. Being independent from the pump allows you to adjust the float level without moving the pump.



sumppumpswitchattachedSump Pump Vertical Float – Integral

The same concept as the independent vertical float except the switch is an integral part of the sump pump.

This makes switch replacement more difficult and eliminates the ability to adjust the position of the float without adjusting the position of the pump.





Sump Pump Pressure Sensor Switch

The black bar you see mounted on the side of the is a pressure sensor. As the water rises the pressure increases and turns on the pump.

The main draw back to these switches is they are hard to test without adding water. All of the other sump pump switches listed above can be manually activated without water.