Installing a new Fluidmaster fill valve requires no special tools. The installer does most of the work, including tightening the coupling nut with his hands. Removing the old valve and tightening the supply line to the cut-off valve may require an adjustable wrench or pliers.
A fill valve allows water to refill the tank of the toilet after each flush, preparing it for the next one. It has a float that the water lifts as the tank fills. When the float reaches the set level, it shuts off the water flow to prevent overflowing. After installing a new valve, it is sometimes necessary to adjust the float to ensure the water level remains below the overflow pipe.