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Drinking Water Quality

Lake Springfield is the source of Springfield's domestic water supply. It provides drinking water to approximately 147,750 people who, altogether, use an average of about 22 million gallons of water each day. Water taken from the lake undergoes a rigorous purification and testing process—to ensure it is free of harmful bacteria and particulate matter—before being distributed for domestic use to the utility's water customers.

Water Testing

Throughout the water purification process, chemists and plant operators at the CWLP Water Purification Plant perform approximately 70 analytical tests on the purified water each day to ensure it meets or exceeds Illinois Environmental Protection Agency (IEPA) standards for microbiological and chemical content. Many samples are also sent to the IEPA for chemical analysis. In this way the utility assures that the product leaving the Purification Plant will be of the highest possible quality.

Altogether the levels of about 150 different chemicals and water quality parameters are checked and the analytical results are compared to the maximum contaminant level (MCL) allowed for chemicals by the IEPA. As of the most recent test dates, in all cases, chemical levels in Springfield's drinking water fell below the MCLs established by the IEPA.

Among the chemicals tested for are: alachlor, ammonia, arsenic, atrazine, barium, benzene, calcium, carbon tetrachloride, chlordane, chlorine, cyanide, DDT, heptachlor, iron, lead, lindane, magnesium, manganese, mercury, nickel, nitrate, selenium, sodium, sulfate, vinyl chloride, and zinc.

Preventing Backflow Contamination

In spite of CWLP's efforts to produce pure, safe drinking water, Springfield's drinking water can be placed at risk by contaminants that "backflow" into the system from our customers' homes or businesses. It's up to all customers to take the necessary steps to protect our water supply from this type of problem by making sure their plumbing systems are equipped with working backflow prevention devices. For more information about backflow contamination and how you can help prevent it, see our online pamphlet below.
Protecting Against Backflow Contamination Pamphlet Take our 2018 Survey

Water Quality Reports

Each spring, CWLP prepares a Water Quality Report for our customers detailing the results of drinking water tests performed during the preceding year. An announcement of the availability of the annual report is enclosed in the May or June billing envelopes of all customers who receive a CWLP bill. The report is available online or, upon request, in paper form to any CWLP water consumer. See our most recent Water Quality Reports online below.
WQR2013 WQR2014 WQR2015 WQR2016 WQR2017

To obtain a printed copy of the report by mail, call the Water Purification Plant, 217.757.8630, or email the Public Information Office at