Why Is My Water Bill So High?

By Naperville Guide · Published October 9, 2026

Short version: why is your water bill so high in Naperville? Mostly infrastructure. The city is charging more because it's decades behind on replacing water mains and is rebuilding its biggest treatment plant — and a state mandate is adding lead-pipe replacement to the to-do list. Here's the verified breakdown, and the part of your bill you can actually fight: leaks.

The rate hikes, in plain numbers

Start with the headline figure from the city's own rates page: since January 2026, the average residential combined water/wastewater bill — for a customer using 750 cubic feet a month — is $118 a month. That's actually still below the DuPage County average of $120, but it's climbing fast, and here's the schedule behind it:

What are you paying for? Two things the city is unusually candid about. First, the pipes: a 2020 evaluation found Naperville more than 50 miles behind on water main replacements. The city has ramped from replacing one mile of pipe a year to three — but the consultant recommended ten. Second, the Springbrook Water Reclamation Center: the upgrades now underway are the largest capital improvement project in the city's history, estimated at more than $180 million through 2030, driven by mandated nutrient-removal standards and capacity expansion. Old pipes and one giant treatment plant: that's your bill.

Reading your own bill

Naperville's bill has more line items than most people read. The ones that matter:

• Water Capital Charge — a fixed charge that funds equipment and facility maintenance "regardless of how much more or less water is used." This is where the pipe-replacement program lives on your bill.
• Phosphorous Charge — funds half of the state-mandated Springbrook improvements to cut phosphorous discharge. A direct line from environmental regulation to your wallet.
• Wholesale water (DWC/City of Chicago) — the city buys Lake Michigan water through the DuPage Water Commission, and the wholesale rate is a direct pass-through. The Commission sets it each April, effective May 1. When Chicago or the Commission raises rates, it lands on your bill with no city markup in between.
• Outside-city surcharge — unincorporated Naperville customers pay 30% more on water rates.

If your bill jumped and none of these explain it, the usage side is where to look next.

The lead-pipe mandate most homeowners haven't heard of

Illinois law is quietly adding another infrastructure bill. The Lead Service Line Replacement and Notification Act (Public Act 102-0613, effective January 2022) requires every community water system in the state to inventory its lead service lines and replace all of them — on a mandatory schedule: utilities with 1,200 or fewer lead lines must replace at least 7% a year (done in 15 years); bigger systems get 17 to 34 years depending on count. Final replacement plans are due to the Illinois EPA by April 15, 2027.

Two details that hit homeowners directly: galvanized steel service lines count as lead under the Act, and partial replacements are banned — when a line gets replaced, the whole line goes, and the utility has to offer the homeowner a way to pay for their side that low-income residents can actually afford. If your house was built before the mid-1980s and still has its original service line, this law is about you — and statewide, the funding to do it all doesn't exist yet, which is exactly the kind of pressure that eventually shows up in rates.

What you can actually do about your bill

The rate hikes are set by the city council; you can't negotiate those. But leaks are the silent half of many "why is my bill so high" stories, and they're yours to fix. The EPA's WaterSense program says 5 to 10 percent of US homes have easy-to-fix leaks wasting 90 gallons a day or more — and fixing household leaks saves about 10 percent on water bills.

• The 10-minute toilet test. Toilets are the most common silent leakers. Put a few drops of food coloring in the toilet tank, wait 10 minutes without flushing — if color shows up in the bowl, the flapper is leaking and needs replacing. Flush right after so it doesn't stain. (EPA WaterSense protocol.)
• The meter test. Read your water meter, then don't use any water for two hours and read it again. If it moved, you have a leak somewhere — a fixture, a hose, or underground.
• The winter benchmark. In a cold month like January or February, a family of four using more than 12,000 gallons a month almost certainly has serious leaks, per the EPA. Check your bill's usage line, not just the dollar amount.
• Know your baseline. The average American uses 82 gallons a day at home; the average family tops 300 gallons a day, with bathrooms accounting for more than half of indoor use. If your household is far above that, something is running that shouldn't be.

And if a sudden spike follows no change in your habits, check for leaks first — then call the city's billing line at (630) 420-6137 to ask about your options. For context on the other utility squeezing Naperville wallets, we broke down why electric bills are so high — and whether data centers could raise water bills — earlier this week.

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