According to documents filed with the PSC, the utility needs more money to pay down nearly $245 million in debt while funding an ongoing project to replace some 400 miles of aging cast iron water mains.

"We need to make improvements ... and can't responsibly borrow anymore," said utility spokesperson Marcus Pearson.

Madison's rates are currently in the top quarter of utilities serving more than 4,000 customers, which range from about $13 a month in Sheboygan to nearly $49 in Elkhorn, according to PSC data. Madison's rates are higher than any comparably sized city and almost twice those of Sun Prairie and Middleton.