Water Sources and Treatment: Customers of the OCWA receive water that originates from Otisco Lake, Lake Ontario, or Skaneateles Lake. Customers located in certain areas may get a mixture of these waters or their source water may vary with changes in seasonal demand. In 2018, OCWA supplied approximately 37.59 million gallons per day to its 340,000 residential and commercial customers located in our five-county service territory (Onondaga, Oswego, Madison, Oneida, and Cayuga). OCWA also supplies water daily to thirty-four large industrial customers and two municipal wholesale water customers. OCWA can also supply water on an intermittent or emergency basis to seven additional municipal water systems.

OCWA treats and delivers water from Otisco Lake; the easternmost and smallest finger lake. In 2018, approximately 17.4 million gallons per day or 46.3 % of OCWA’s water came from Otisco Lake. The customers receiving water originating from Otisco Lake are mostly located in the southern and western half of Onondaga County.

OCWA also treats and delivers water originating from Lake Ontario near the City of Oswego to our Ontario Water Treatment Plant.  In 2018, approximately 19 million gallons per day or 50.5% of OCWA’s water came from Lake Ontario. The customers receiving water originating from Lake Ontario are mostly located in the northern and eastern half of Onondaga County. OCWA customers in Madison, Oneida, Oswego and Cayuga counties receive all their water from Lake Ontario.

The City of Syracuse Water Department has the responsibility of treating and delivering water originating from Skaneateles Lake. In 2018, approximately 1.2 million gallons per day or 3.2 % of OCWA‘s water came from Skaneateles Lake water purchased from the City of Syracuse Water Department through various supply connections. OCWA uses this water to supplement areas close to the city boundary when needed. OCWA customers living in Nedrow, Southwood and the Jamesville area, get water from Skaneateles Lake exclusively.

The first step in water treatment is to protect the source. OCWA and the City of Syracuse have been conducting ongoing watershed inspection, monitoring, and educational programs for a number of years. These programs are in conjunction with the State and Onondaga County Departments of Health. OCWA and the City of Syracuse both monitor lake conditions on regular intervals prior to treatment.

The New York State Department of Health has completed a Source Water Assessment Program in order to better recognize potential sources of contaminants in every water source used throughout the State. This assessment can be found in the SWAP Summary for OCWA.

OCWA has two intake pipes located in Otisco Lake. The water entering these pipes is immediately disinfected with either sodium hypochlorite or chlorine dioxide to discourage the growth of zebra mussels. The water then travels, by gravity, approximately five miles to OCWA’s Water Treatment Plant located in Marcellus, NY. Water first enters the Rapid Mix tank where a coagulant (polyaluminum chloride) is added. After 30 seconds of mixing, the water enters the Contact Basins where the calm conditions allow the coagulant to make the small particles adhere together forming larger particles. Some of these particles settle and are cleaned out later. The contact time in these basins also allows powdered activated carbon (used only when needed) to adsorb organic taste and odor causing chemicals. After about one hour of contact time the water enters the filters. Particles are removed as the water passes through one of six multimedia filters. These filters consist of granular activated carbon, silica-sand, and hi- density sand. The filters are washed periodically and the water used to do this is collected in lagoons and allowed to settle. It is then recycled back to the start of the treatment plant to be treated again. After filtration, the water is again disinfected with sodium hypochlorite and fluoride is added. The water is stored in large tanks located at the treatment plant to provide adequate contact time for the chlorine to work. Once the water leaves the tanks orthophosphate is added to provide a coating for the pipes in the distribution system and in your home. This is done in order to prevent the leaching of lead and copper from your pipes and into your water.

OCWA’s Ontario Water Treatment Plant pumps water from Lake Ontario through an seven foot diameter intake it shares with the City of Oswego. Upon entering the Raw Water Pumping Station, lake water is treated with carbon dioxide to suppress pH thereby increasing the effectiveness of chemical coagulation. Potassium permanganate is applied seasonally to raw water for taste, odor control and pre-oxidation. The water is pumped approximately two miles to OCWA’s treatment plant. Water entering the plant is treated with sodium hypochlorite (disinfectant) and polyaluminum chloride (coagulant) and is flash mixed. The water then enters three contact basins where slow mixing allows small particles to accumulate and form larger, more readily filtered particles. After about 2 hours of contact time, the water flows into dual media filters consisting of granular activated carbon and filter sand whereby particulate contaminants are removed. After filtration three treatments are applied: fluoride to reduce tooth decay, sodium hypochlorite to disinfect and sodium hydroxide for corrosion control.

The City of Syracuse does not filter the water that enters their intakes located in Skaneateles Lake. The city has been granted a waiver to provide its customers with unfiltered water subject to strict conditions set by the New York State Department of Health. These conditions include water quality monitoring, backup disinfection, and watershed protection. The City of Syracuse Water Plant is located in the Village of Skaneateles. There they provide disinfection by the addition of chlorine, and fluoridation. Water then flows by gravity into the City’s storage reservoirs. Orthophosphate is added to the water (for lead and copper control) as it leaves these reservoirs and it is disinfected again by the addition of sodium hypochlorite.

The sources of drinking water (both tap water and bottled water) include rivers, lakes, streams, ponds, reservoirs, springs and wells. As water travels over the surface of the land or through the ground, it dissolves naturally occurring minerals and, in some cases, radioactive material, and can pick up substances resulting from the presence of animals or from human activities. Contaminants that may be present in source water include: microbial contaminants; inorganic contaminants; pesticides and herbicides; organic chemical contaminants; and radioactive contaminants.
Click Here for Water Source Map

Towns, cities Water source Villages Water source
Camillus Otisco Baldwinsville Ontario*
Cicero Otisco/Ontario Camillus Otisco
Clay Otisco/Ontario E. Syracuse Otisco/Ontario
DeWitt Otisco/Ontario/Skaneateles Fayetteville Ontario
Elbridge Otisco Liverpool Otisco/Ontario
Geddes Otisco/Ontario/Skaneateles Manlius Ontario
Lafayette Ontario Marcellus Otisco
Lysander Otisco/Ontario Minoa Otisco/Ontario
Manlius Ontario/Skyridge Wells N. Syracuse Otisco/Ontario
Marcellus Otisco Solvay Otisco
Onondaga Otisco/Skaneateles
Otisco Otisco
Pompey Ontario
Salina Otisco/Ontario
Skaneateles Otisco
Spafford Otisco
Syracuse Otisco/Ontario*
Tully Tully Valley Springs
Van Buren Otisco/Ontario
*Emergency connection only


Towns, cities Water source Villages Water source
Constantia Ontario Central Square Ontario
Fulton Ontario* Phoenix Ontario
Granby Ontario
Hannibal Ontario
Hastings Ontario
Minetto Ontario
Oswego (City) Ontario*
Oswego (Town) Ontario
Schroeppel Ontario West Monroe Ontario
Scriba Ontario* Volney Ontario
*Emergency Connection Only


Towns, cities Water source Villages Water source
Lenox Ontario Canastota Ontario
Sullivan Ontario Chittenango Ontario
Oneida (City) Ontario*
*Emergency connection only


Towns, cities Water source Villages Water source
Verona Ontario Sylvan Beach Ontario
Vienna Ontario
Annsville Ontario Vienna Ontario


Sterling Ontario