What is a float valve?

A float valve controls water inflow into a tank by responding to water level. As the tank fills, a hollow ball or bulb floats upward on the rising water surface. This floating mechanism is connected to a valve stem that gradually closes an internal valve passage. When the water reaches the desired height, the fully risen float shuts off the valve completely, stopping any further inflow. If the water level drops (such as when a tap is opened downstream), the float descends and reopens the valve to refill the tank.

In Klang Valley homes and commercial properties, float valves are standard in rooftop tanks and ground-level storage cisterns. They prevent overflow damage, reduce water waste, and eliminate the need for manual tank management. Without a functioning float valve, tanks overflow into ceilings or spillway systems, damaging structures and wasting treated water.

Common failure signs include continuous water trickling into the overflow pipe, a tank that never fills completely, or water pooling above a tank when it should be sealed. Float balls may corrode or develop pinhole leaks and sink, preventing the valve from closing. The valve seat can accumulate sediment or mineral deposits, stopping it from sealing properly. Mechanical wear in the float rod arm or linkage may also prevent smooth operation.

If your float valve is malfunctioning, water tank and pump service providers can inspect, repair, or replace the unit to restore proper tank management.