Rojo Part fill Valve is a low flow valve intended for the use in rainwater harvesting tanks. The purpose of the float valve is to automatically maintain a low level of water in the tank during periods of low rainfall. This allows services fed by the tank to continue while leaving capacity in the tank for refilling by the next rain. Available in 3/4" and 1/2" inlet sizes. NSF 372 Certified for potable water systems. Valve has longer threads and back nut for easy installing through a tank wall.