Water Treatment
Shaft 22 water is fluoridated and chlorinated by New York City at Kensico Reservoir.  Caustic soda is added at Shaft 22 to increase the pH of the water.  The Water Works provides additional chlorination at its Larchmont Station and adds a blended poly-orthophosphate as a corrosion inhibitor at that point.

Water is pumped from Rye Lake at two locations.  The Lake Street Station furnishes water to West Harrison, the former Harrison Water District No. 1 system that was acquired by the Water Works effective January 1, 2005.  Treatment at that location consists of chlorination and zinc orthophosphate for corrosion control.

The Rye Lake Station, located about 1,600 feet east of the Lake Street Station, furnishes the rest of the Water Works system with water that is fluoridated, chlorinated and provided with a blended poly-orthophosphate at the source.  After the water passes through the Purchase Tanks on Purchase Street in the Town of Harrison, caustic soda is added for pH control.