Niagara's Toilet Fill Cycle Diverter is an easy-to-install, inexpensive water saving product for your toilet tank that saves up to 50% of the fill cycle water - up to 1/2 gallon per flush. The diverter works by redirecting a majority of the water that would normally drain down the overflow tube back into your toilet tank during the fill cycle. Save money and make your toilet more efficient by conserving water from flowing down the drain.