Water Treatment Plant

Who We Are

The City of Ithaca Water Treatment Plant has been proudly serving the City of Ithaca and a few surrounding areas since 1903.

Located along a reservoir on Six Mile Creek, the facility provides safe, clean water to over 35,000 residents in the city area.

Six Mile Creek: Our Watershed

Six Mile Creek is more than just a beautiful waterway in our backyards. It is part of the Six Mile Creek watershed, an area that spans 46.5 square miles of mainly forested land. Its headwaters begin in the Towns of Caroline and Dryden. Learn more about our local watershed. 
Potters Falls


The New York State Health Department prepared a Source Water Assessment Report for every surface drinking water source for the state. The report for Six Mile Creek was completed in 2004 and can be found here. The main vulnerabilities found at the time were excessive sediment and turbidity entering and filling the drinking water impoundment and an elevated risk of microbial and protozoan contamination due to the amount of pasture land in the watershed.

Parts of the drinking water plant rebuild project address these issues. Switching from sand and coal dual media filtration beds to membrane filtration effectively removes 100% of microbial and protozoan from the drinking water supply as the pore size on the filters is smaller than the organisms. Another technological upgrade was the change from gravity settling to inclined plate settlers. These settlers dramatically increase solids removal and are well suited to removing the silts and clays typical in our source water. Finally, the drinking water impoundment (reservoir) is scheduled to be dredged in 2020. A schedule for maintenance dredging will be developed to prevent future filling of the reservoir.

Making Your Water Safe to Drink

To ensure the highest quality possible, the City of Ithaca Water Treatment plant uses a six-step process to treat the water coming in from Six Mile Creek.
  1. Pre-treatment: Chlorine and coagulating agents are added to the incoming raw water to disinfect and remove impurities.
  2. Mixing: The water is rapidly mixed to distribute the treatment agents evenly.
  3. Coagulation and Flocculation: The water flows into large basins where chemicals react with impurities in the water (coagulation), causing them to form larger, heavy clumps called "floc" (flocculation.
  4. Sedimentation: The flocculated water flows into basins where these heavy clumps fall to the bottom.
  5. Filtration: Currently, the water flows through layers of anthracite coal and sand to further remove particulates. However, the facility will soon be upgrading to membrane technology, which is capable of removing even smaller particulate matter.
  6. Post-treatment: Chlorine is added to prevent bacterial growth in distribution pipes, as well as a corrosion inhibitor that helps protect the distribution pipes.

From Us to You

Water from the reservoir flows into the treatment plant by gravity. After treatment, finished water is distributed to the public through a distribution network consisting of roughly 85 miles of ductile iron and cast iron water mains ranging in diameter from 4 - 20 inches. The distribution system also includes 3 pumping stations and 6 water storage tanks. The final leg of the journey from the main in the street into your home or business is completed via a copper water service pipe 1/2 - 2 inches in diameter.