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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.
Lead Safety

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. See our most recent Water Quality Reports online below.
WQR2014 WQR2015 WQR2016 WQR2017 WQR2018 WQR2019 WQR2020 WQR2021 WQR2022 WQR2023

To obtain a printed copy of the report by mail, call the Water Purification Plant 217.757.8630, ext. 1702, or email

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 Survey

Distribution System Flushing

The Springfield Fire Department, in coordination with CWLP conducts annual testing of the fire hydrants to ensure each is operating efficiently for fire protection purposes. Water can become discolored in service areas located in the vicinity of the hydrant tests.

If discoloration occurs or during testing to avoid issues, residents should run water from an outdoor hose connection preferably, or through an indoor tap, until the water turns clear. Clothes washing should be delayed until the tap water runs clear to avoid discoloration. In most instances, the water will clear in approximately five minutes.

For information on locations and times for the annual hydrant testing, residents may call the Springfield Fire Department at 788-8474. CWLP customers may call Water Dispatch at 789-2323 ext. 2 if discoloration persists or for any other questions on water quality.

Taste & Odor In Drinking Water

When certain ecological conditions present in a water reservoir, an increase in algal compounds can occur, resulting in what some may notice and describe an earthy, musty or dirty taste and odor to the drinking water. While not aesthetically pleasing, the algal compounds that cause this type of taste and odor issue are non-toxic and not considered a risk to public health. These compounds also do not diminish the ability of a water provider to meet water quality guidelines for health standards.

While these compounds are not toxic or against any water quality guidelines for health standards or drinking water regulations, CWLP works hard to meet customer expectations for the water’s aesthetic characteristics—its taste, odor and appearance. CWLP’s water treatment process feeds powdered activated carbon to reduce taste and odor compounds in the finished drinking water. To further address the taste and odor issues, the Water Plant can increase its powder activated carbon in the treatment process and alter the depth of its raw water intake in an attempt to minimize the issue. Water Distribution can also enact distribution system flushing to move water, which can be helpful near the conclusion of taste and odor events.

What is making my water taste or smell earthy or musty?
Lake turnover, a normal event for surface water supplies, occurs in a reservoir when the water from the top of the lake to change places with the water on the bottom of the lake. With fall temperature changes, as water cools on top of the lake, it becomes more dense, causing it to sink. This dense water forces the water from the bottom to rise. Lack of water movement in a reservoir can exacerbate the turnover effect and increase the compounds that cause taste and odor issues.

Other ecological conditions and influences in a reservoir can also lead to increased algal compounds. Like temperature, the amount of precipitation or runoff, or movement of water in a reservoir can also be factors in increasing compounds. For Lake Springfield, the retirements of Dallman Power Plant Units 31, 32 and 33, which no longer pump water for cooling or discharge hot water into the lake appear to correlate with exacerbation of the higher levels of algal compounds in some instances. Dallman 4 doesn’t use lake water for cooling or discharge water into the lake.

With lake turnover or these varied ecological conditions, algal compounds from naturally occurring blue green algae result in a change in the taste and odor. The algal compounds, Geosmin and Methylisoborneol (MIB) found in naturally occurring blue green algae have been identified as the cause for recent taste and odor issues in Lake Springfield.

On September 21, 2021, CWLP presented information on status of lake turnover, impacts and potential solutions.
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Is my water safe to drink?
Yes. These algal compounds are non-toxic and do not impact drinking water safety or pose any violation of a water quality health standard or regulation. Although the water can have an off taste or odor to some described often as earthy, musty or dirty, it is safe to drink. Chilling tap water before drinking can greatly reduce taste issues.

Customers sensitive to the taste and odor issues may find drinking chilled water from a pitcher after refrigeration may be more pleasing.

What does CWLP use to make the water taste better?
The Water Plant can increase its Powder Activated Carbon in the treatment process, alter the depth of its raw water intake and conduct plant washouts to address when the issue arises. Year-round CWLP and its partners implement Best Management Practices in the Lake Springfield Watershed to reduce runoff and nutrients into the reservoir, which include those that cause algal compounds to increase.

In 2022 CWLP entered into a contract with Crawford, Murphy & Tilly, Inc. for a study of solutions for taste and odor issues. The result of this study are expected in summer 2023. This contract followed the City Council’s deferred action on CWLP purchasing and placement of circulator equipment known as, “Solar Bees,” on Lake Springfield—a measure proposed to address taste and odor issues.

Is there anything I can do to make the water taste better?
Chilling tap water before drinking can reduce taste issues for some. Adding a slice of lemon to the water sometimes helps as well. A home charcoal filter may help but it is not likely to remove the taste or odor entirely. The charcoal in a home filter uses the same material (granular activated carbon) as the water treatment plant does, which is only able to resolve most but not all, of the taste and odor causing compounds.

Where can I report water issues or ask questions?
Contact our 24-hour Water Dispatch at 217.789.2323 ext. 2 and make a report with your contact information and address or email

Lake Circulators “Solar Bees” Proposed To Improve Lake Water Health

On March 9, 2022 CWLP and Ixom Watercare presented information to members of the Springfield Lake Shore Improvement Association members on the use and placement of circulator equipment, “Solar Bees,” on Lake Springfield—a measure proposed to address lake turnover and resulting water taste and odor issues as occurred last late summer to fall.

From the presentation, one question asked not anticipated was if this area of the lake where the circulators would be placed would become a no wake zone. The answer to that question is no. There is not a plan to dedicate this area of the lake as a no wake zone with placement of any lake circulators.
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At the February 1, 2022 City Council meeting, CWLP and Ixom Watercare presented information on lake circulation equipment as a potential solution to alleviate impacts of lake turnover and overall improve lake water health.
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On September 21, 2021 City Council Meeting, CWLP presented information on status of lake turnover, impacts and potential solutions.
Watch Video  View PDF