Naperville residents could face a 70 percent water rate hike if a proposed increase is approved in Chicago, City Manager Doug Krieger said Friday.

The source of much of the region’s drinking supply, Chicago pumps water from Lake Michigan — which is then distributed to many suburbs. Now, Chicago Mayor Rahm Emanuel says it is only fair to ask all who rely on that water source to pay for repairs to city’s century-old distribution system.

But Krieger said residents could stand to pay millions to fix that infrastructure, a burden he said is not suburban Naperville’s problem.

“It would be millions of dollars coming from Naperville residents to fix a Chicago problem,” he said. “I believe our rate should be based on what it costs them to deliver water, and we should not be penalized for their failure to maintain their infrastructure.”

He said early estimates from the Department of Public Utilities – Water show a 70 percent hike in rates over the next four years if the plan is approved. Based on a current average of $36.80 for a water bill in the city, in 2015, the amount would jump to $62.56.

Krieger said the DuPage Water Commission will first have to determine the impact on its rate, and the city will have to conduct a rate study before changes are made.

“Ultimately a change this significant would cause us to revisit out rate study,” he said, adding the cost will trickle down to residents. “The increases would be so significant they would not be able to be absorbed by operational changes here.”