Float Switch act as a Level sensor, i.e. a device which helps in detecting the liquid level in a tank. The switch act as an alarm, indicator, to control the pump or to control other devices. 


1. The first type of Float switches uses Mercury to switch within a hinged float. 

2. The second type is a float that actuates a microswitch by raising the rod.

3. Third uses magnet surrounding the tube with reed switch mounted in a tube.   

Float switches are most commonly used in the sump pumps and condensate pumps where the switch helps in detecting the level of the liquid in the pump and tanks. It energizes the electrical pump which helps in pumping the liquid out till the level of the liquid is reduced which further turns the switch off.  Most of the float switches are adjustable which includes substantial hysteresis; which means that the turn off point would be lower than the turn-on point. This helps in minimizing on-off cycles of the pump.

Few Float switches contain switches of two stages. When the level of the liquid touches the triggering point, the associated pump activates. In this case, if the pump fails to perform its working due to any of the reason and the level of the liquid continues to rise above the triggering point, the second stage starts. This stages can perform a variety of the functions, from switching of the liquid being pumped to triggering of an alarm or both.

Float switches if installed minimizes the opportunity of formation of dirt on the float that would hinder its motion. Float switches resist the corrosiveness process as they are made with selective materials. Apart from that, properly selected float helps in sensing the interface levels between the liquids with different densities.


Earlier Float switches used to work by process of opening and closing dry contacts which helps in sending electrical signals that further helps in setting off low water level alarm. They were using the Magnetic reed switches that use to complete the circuit when the float reaches the lowest point in the water. The magnets then use to get disconnect once the water reaches the appropriate level once again, leading to opening the circuit back up. The major drawback of the usage of these float switches was that they didn’t have many operations and were to be replaced in the short span of the time, making them very expensive to use. 

NOW: Float witches have gone through numerous development making them more reliable and suitable for the consumers and also making them far less expensive. Float switches are performing numerous functions now, for instance: Float switches use probe which helps in detecting or sensing the water levels in the tanks. The sensor probes acting as their own sensors do not pass the electricity which further helps them from getting deteriorated. Float switches also possess different alarm system that can be single point alarm or multi-point alarm.


In Single point float switch, there is a low alarm sensor that triggers the Led light on control board.

Multipoint Float switch: Low alarm triggers Led light which gets turn on and sending the signal to turn on the auto water pump refilling the water back to adequate water level. The process could also be programmed to halt after the water level has reached fill stop probe. 

The working of the float switch depends on detecting the water level and providing a signal to the computer telling it how to act detecting the level of the ate table in the tank. For instance, if the level of the water in the tank is low, float switch detects the level and signals the system about the low level of the water table and signaling it to fill the water level. If it detects that the level of the water in the tank is increasing the adequate level pre-programmed in the tank, it gives the signal and it automatically drains the excessive water, brings it back to the adequate level as programmed in the water tank. This helps in performing the task of the level of the water to an adequate level automatically without any manual help. Nearly any storage tank that uses the float switch can make use of this technology.


VERTCAL ACTION FLOAT SWITCH :                       

a) Inexpensive

b) Great Quality

c) Floats above water 

d) switch does not get stuck or jam


a) Expensive but used by professionals

b) Immersed underneath 

c) works on water pressure

c) does not stuck


a) most commonly used

b) used for pedestal sump pump 

c) remains above water

d) no worries absit power or electricity


a) often called flood free switch

b) relies on water pressure to activate probe wire inside

c) have a back up incase of any problem 

b) Useful in SMALL or NARROW Sump BASIN.

c) Uses more electricity