Chicago officials state the average cost to replace a lead water service line is about $31,000. The Environmental Protection Agency's national estimate for lead line replacement is $4,700 per line. Engineering firm CDM Smith estimates the national average cost at $12,500 per line. A survey of 18 cities found average replacement costs between $6,000 and $25,000, with most reporting figures less than half of Chicago's stated cost.

Chicago has more than 400,000 lead water service lines, representing the largest known inventory in any U.S. city. Replacing the entire inventory at the current rate would cost more than $12 billion. A federal mandate requires the removal of every lead pipe within roughly 20 years.

Cyndi Roper, a senior policy advocate with the Natural Resources Defense Council's safe water initiative, called the situation "absurd." "It is absurd," Roper said. "You can't play victim to your own policies. … You actually can make changes to bring the cost down." She added, "It seems like the story here is how hard you have to work to get information that's needed in order to figure out why the costs are so high."

A review of program documents, contracts, and interviews identified inefficient early contracts, cumbersome permitting requirements, and reliance on one-off replacements as key contributors to the high costs. Department of Water Management officials were unable to provide consistent figures for replacement costs and the number of lines replaced, and did not clarify whether the department systematically tracks replacement costs.

Chicago replaces lead service lines through emergency repairs, capital improvement projects, equity initiatives, and block replacements. Between 2021 and the end of 2025, block replacement programs accounted for 3% of the approximately 15,000 lines replaced. Nearly all replacements during this period were conducted piecemeal, primarily during leak and break repairs. Water department officials stated the average per-line cost for block-level work is approximately $34,000, while one-off replacements average $39,000.

Under Illinois state law, municipalities must obtain property owners' permission to replace private lead lines, and partial replacement is forbidden as it can flush more lead into drinking water. State lawmakers passed a bill in May granting city plumbers access to private lines without owner permission. The measure awaits Gov. JB Pritzker's signature.

Homeowner Craig Hines received a preliminary quote of $25,000 to replace a single lead service line, with permits estimated to cost between $5,000 and $7,000. "These fees seem so exorbitant when it's like, this was a city screw-up," Hines said. He added, "I just cannot believe that the permitting fees are so high to help fix a problem that the city created." Replacing a single lead line in Chicago can require permits from the water and transportation departments, in addition to inspection-related charges. Permit fees vary based on the type of street and pipe size. The water department waives its permit fees when the city funds replacements, and some property owners may qualify for a city program waiving up to $5,000 in fees. Water department spokesperson Megan Vidis stated in May that she would not answer further questions on the topic.

U.S. Senator Tammy Duckworth said she was not aware of the cost discrepancy but expressed hope for transparency from the city regarding the high costs. "Cities just need to get their act together and get this done, and we've been slow to do this in Chicago," Duckworth said. She added, "Other cities have moved much faster than us."