The city has known for at least six years that many of its water mains are located too close to sewer lines, violating a state law aimed at protecting drinking water from contamination.
The city discovered in 2019 that Chicago’s Water Department was not complying with state environmental requirements to keep a minimum distance between underground water mains and sewer lines, according to documents released by city Inspector General Deborah Witzburg on Wednesday.
To date, there’s no evidence that the city’s drinking water has been contaminated.
According to Witzburg, the water pressure going through the underground pipes reduces the risk of contamination from sewer lines even though the piping is so close together. However, a loss of pressure — a problem that has occurred in recent years — poses a public health threat from possible contamination, Witzburg said in an advisory.
“Parts of the city’s network of water mains have lost full pressurization multiple times in recent years, raising the specter that structural protections against a contamination event might fail,” Witzburg said in a December letter to Chicago Department of Water Management Commissioner Randy Conner.
Witzburg said that the Water Department should also “take additional steps to improve transparency around and facilitate public understanding of this matter.”
Water pressure can be lost when a water main breaks or due to other problems.
A boil order was issued in Auburn Gresham, Beverly and Morgan Park last July after a leak in a high-pressure water main inside the more than century-old Roseland Pumping Station.
That order affected about 20,000 homes and businesses, which was described at the time as a very large number for such an incident.
The city provided bottled water for residents and warned to boil water before drinking it or using it to wash food.
The Roseland Pumping Station had another mishap that resulted in low water pressure in May 2021 and that also required a boil order.
Under state law, the city’s water mains should be laid out horizontally at least 10 feet from any sewer lines or sewer connections.
In 2019, the city discovered “widespread noncompliance” with the state law, Witzburg said in her advisory.
In a reply letter to Witzburg this month, Conner said that the city performs “continuous water pressure monitoring and leak detection.”
As for making the public aware, Conner added that his department “shares a commitment to public transparency and to ensuring that information is clear, factual and does not cause undue alarm where no significant risk is posed.”
He noted that the city is working with the Illinois Environmental Protection Agency to correct the issue.
Illinois EPA entered into an agreement with the city that called for the water department to submit a “corrective action plan,” said agency spokeswoman Kim Biggs.
Work on the plan continues, Biggs said, adding that “the Illinois EPA has never ruled out taking additional enforcement action if necessary.”