How Does a Sump Pump Float Switch Work?

By: John Garcia | Date Posted: December 28, 2021

Controlling your sump pump could be very annoying, especially when you don’t know when to start the pump and when to turn it off. In that situation, using a float switch with a sump pump will be an excellent way to control your pump.

Typically, a float switch automatically turns on and off the pump when the water level reaches a particular level in your basement. This way you can keep your basement always water-free. You may be wondering now how this switch works.

Basically, this switch has a level sensor above the water, which fluctuates according to the water level in your sump pit. When the water level increases, the level sensor reaches a certain level and turns on the pump. Besides, the sensor drops and turns off the pump when the water descends.

Sump Pump Float Switch – What Is It?

Sump Pump

The sump pump is a crucial machine to keep your basement water-free. But when it is manual, turning on and off the pump could be very irritating. This is because you don’t know when to turn off the pump and when to turn it on. As a result, your basement could be flooding anytime.

In that case, a float switch comes in to get rid of this situation. Typically, it is a tool to control a sump pump. According to Plumbingpoints, a float switch comes with a sensor that can detect water levels in the basement. When the pump needs to turn on, the sensor signals to the float switch to turn on the pump.

Advantages of Using Sump Pump Float Switch

Below, we have pointed out the advantages of using a sump pump float switch. This will also help you know why your sump pump needs a float switch.

  • Afloat switch will enable your sump pump to turn on and off automatically.
  • It helps to keep you away from the hassle of manually turning on and off your pump.
  • This switch helps to keep your basement always dry without your intervention.
  • Using a sump pump with a float switch will make your pump last longer.
  • As this type of switch is very functional, your sump pump will fail less, resulting in minimal cost in the long run.
  • A reliable sump pump float switch is easy to afford and requires a minimal setup procedure.

How Does a Sump Pump Float Switch Work?

As we said earlier, a sump pump float switch comes with a float or level sensor that helps to detect water levels. This sensor is set up in your basement perpendicularly and connects with a switch.

This switch usually connects directly to sump pumps. When the water is raised or down, a level sensor fluctuates according to the water level.

Basically, once the water level reaches the upper, the level sensor passes a conductive signal to the main float switch. After that, the float switch triggers a sump pump to turn on for draining the basement. On the contrary, a float switch triggers the sump pump to turn off when the lower level of water is reached. A sump pump remains turned off until the water in your basement rises again.

Different Types of Sump Pump Float Switch

There are different types of sump pump float switches you will find on the market. Although the basic things of all float switches are the same, you have to pick one that meets your requirements. For your help, below, we have outlined some common types of float switches.

Vertical Switch

Among different types of float switches, vertical switches are the most popular and commonly used. This switch controls a sump pump in a quite straightforward way.

It comes in three different portions: a housing, a composite float, and a rod. The floating component is connected through a rod to a switch. Once the floating component has risen, the rod pushes against a lever that functions the electric switch.

Tethered Switch

Tethered Switch

The tethered switch is also a popular float switch with mercury style and piggybacks features. These switches are most outdated and relatively cheap. A tethered switch mechanism contains a floating hollow body with a steel ball inside.

This floating element is connected to the sump pump with a cord. Once the water pivots, the internal ball moves and triggers the electric switch.

Diaphragm Switch

The installation procedure of this float switch is very easy as it contains a piggyback plug. Unlike any other float switch, a diaphragm switch is operated by pressure. That’s why this switch is attached to the side of a pump or at the very bottom of the body.

When basement water is raised, the pressure on the switch increases. Once the pressure arrives at a specific point, the switch triggers to turn on a pump. Conversely, when the water level drops, the pressure decreases, and the pump turns off automatically.

Electronic Switch

The electronic switch is sometimes called the flood-free switch. This type of switch doesn’t have any moving components. It employs a probe attached at the level you wish the pump to switch on.

You can easily adjust and preset your pump’s run time through the control box. Besides, you will find another kind of electronic switch on the market that utilizes a single or two floats. These sensors help to determine the float location and turn on or off the pump accordingly.

How to Pick the Right Sump Pump Switch

How to Pick the Right Sump Pump Switch

As you have explored, there are numerous types of float switches you will find. But you should take the right one that can easily control your pump. Otherwise, your pump can be damaged. So, consider the factors discussed below before purchasing a float switch.

Pump Size

If you utilize a float switch rated to control a ½ HP pump to run a 1 or 2 HP pump, the float switch will not last long. Typically, a pump with a higher HP rating requires a float switch that is capable of controlling the higher power. Check out your pump’s amp/HP rating to determine the right size float switch for your sump pump.

Pump Connector

Pump Connector

You will need to select a piggyback float switch if you want to plug it simply into a normal power outlet.

This way, you can plug your float switch into your home’s wall. Also, you have to connect the pump to the back plug on the float switch. For that, before purchasing a float switch, keep in mind the different styles of connectors.

Cord Length

No one may want to splice a cord, as a broken wire can cause severe electrical injury. And if the place is a wet environment like a basement, you should avoid splicing your cord. For that, ensure your float switch contains a long enough cord.

Avoid Narrow-Angle Switch

You will find some float switches that are narrow-angle size and provide low-quality service. As you have to control your sump pump with the switch, choose a wide-angle that offers high-quality service. Another good thing is that the wide-angle switch lasted many years and also helped to extend the pump lifespan.


Using a float switch with your sump pump will be a great way to eliminate the hassle of turning on and off your pump repeatedly. This switch will turn on the pump automatically when the water in your basement hits a particular level. As soon as the water drops to the lower level, the pump automatically turns off.

This way, you can ensure that your basement will always remain water-free without your concern. However, some people may think about how a sump pump float switch works.

For that, we have tried to provide a complete idea about the working procedure of the float switch in this context. Typically, the float switch uses a level sensor that helps to turn on and off a sump pump.

Thank you for reading!


John is the founder and chief editor of Homienjoy. With over 15 years of experience in the home improvement industry, John is passionate about helping homeowners confidently tackle their projects. Holding a civil engineering degree and working as a contractor, project manager, and consultant, John brings a wealth of knowledge and expertise to the Homienjoy community.

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