Chicago Department of Water Management: Infrastructure and Services

The Chicago Department of Water Management (DWM) operates one of the largest municipal water systems in North America, drawing from Lake Michigan to serve millions of residents and businesses across Chicago and dozens of suburban communities. This page covers the department's organizational scope, how its infrastructure functions, the service scenarios property owners and utilities encounter most often, and the boundaries that separate DWM authority from adjacent agencies. Understanding these distinctions matters for anyone navigating water service delivery, infrastructure permits, or billing disputes in the Chicago metro.

Definition and scope

The Chicago Department of Water Management is a city agency operating under the authority of the Mayor of Chicago and governed by Chicago Municipal Code. Its mandate encompasses the treatment, distribution, and metering of potable water, as well as the maintenance of the city's combined sewer and water main infrastructure. DWM serves Chicago's 77 community areas and holds wholesale water supply contracts with more than 120 suburban municipalities in northeastern Illinois, making it a regional water provider well beyond the city limits (City of Chicago, Department of Water Management).

The department operates 2 water filtration plants — the Jardine Water Purification Plant on the North Side and the South Water Purification Plant on the South Side. Together, these facilities have a combined treatment capacity exceeding 1 billion gallons per day, making the Chicago system one of the largest surface water treatment operations in the world (American Water Works Association).

DWM is distinct from the Metropolitan Water Reclamation District, which handles wastewater treatment and stormwater management for Cook County. DWM delivers clean water; the reclamation district processes what leaves the system.

How it works

Water enters the system through intake cribs located approximately 2 miles offshore in Lake Michigan, where it is drawn below the surface to reduce contamination from shoreline runoff. From the intake cribs, raw water travels through tunnels to one of the two filtration plants. Treatment follows a multi-stage process:

1. Screening and pre-sedimentation — physical removal of large debris and suspended solids
2. Coagulation and flocculation — chemical addition (typically aluminum sulfate) causes fine particles to bind and settle
3. Sedimentation — settled solids are removed from the water column
4. Filtration — water passes through sand and anthracite coal filter beds
5. Disinfection — chlorine and fluoride are added to meet U.S. Environmental Protection Agency standards under the Safe Drinking Water Act (42 U.S.C. § 300f et seq.)
6. Pumping and distribution — treated water enters a pressurized network of approximately 4,400 miles of water mains beneath Chicago streets

DWM maintains this distribution grid through a dedicated workforce organized into the Bureau of Water Supply, the Bureau of Water Operations, and the Bureau of Engineering Services. Each bureau holds distinct responsibilities: supply covers treatment and intake; operations covers main maintenance and repair; engineering covers capital planning and infrastructure design.

Water meters — roughly 385,000 across the city as of data published by the City of Chicago — connect the distribution system to individual properties. Meter readings feed into billing administered by the Chicago Department of Finance.

Common scenarios

Property owners, contractors, and suburban utility managers encounter DWM most often in four recurring situations:

Water main breaks — Chicago's aging infrastructure, portions of which date to the late 19th century, produces main breaks throughout the year. DWM dispatches repair crews and issues notices to affected addresses. Residents in impacted blocks may receive boil-water advisories pending pressure restoration and testing.

New service connections — Developers or contractors seeking to connect a new building to the water or sewer system must obtain a DWM permit. This applies to new construction and to properties converting from non-metered to metered service. The Chicago Department of Buildings coordinates on building permits that involve utility connections.

Lead service line replacement — Chicago has an estimated 400,000 lead service lines connecting the water main to residential buildings, one of the highest counts among U.S. cities (EPA, Lead and Copper Rule). DWM administers a replacement program affecting both the city-owned portion (from the main to the property line) and the private portion (from the property line to the meter). Federal infrastructure funding under the Infrastructure Investment and Jobs Act of 2021 (Pub. L. 117-58) has directed resources toward accelerating this replacement cycle.

Suburban wholesale accounts — Municipalities outside Chicago that receive water through DWM wholesale contracts manage their own internal distribution but rely on Chicago's treatment and transmission infrastructure. Billing disputes, pressure complaints, and emergency supply issues route through DWM's wholesale accounts division rather than standard residential channels.

Decision boundaries

Understanding what DWM controls versus what falls to other entities prevents misdirected service requests and regulatory confusion.

DWM vs. Metropolitan Water Reclamation District — DWM is responsible for potable water delivery. Wastewater collection, treatment, and stormwater tunnels operated under the Tunnel and Reservoir Plan (TARP) fall under the Metropolitan Water Reclamation District, a separate elected-board agency with its own taxing authority under Illinois law (70 ILCS 2605/).

DWM vs. Chicago Department of Streets and Sanitation — The Chicago Department of Streets and Sanitation manages refuse collection and street maintenance but does not hold authority over water or sewer infrastructure. Calls about flooding that originates from a broken water main route to DWM; calls about catch basin blockages or street flooding from storm runoff may involve Streets and Sanitation or the reclamation district depending on the infrastructure involved.

DWM vs. Illinois EPA — DWM operates under permits issued by the Illinois Environmental Protection Agency and must meet federal Safe Drinking Water Act standards enforced through the Illinois EPA as the primacy agency. Regulatory violations, enforcement actions, and permit conditions are within Illinois EPA's jurisdiction, not DWM's.

Scope and geographic coverage — DWM authority applies within the corporate limits of the City of Chicago for retail water and sewer service. Suburban municipalities under wholesale contracts receive treated water at city boundary metering stations but operate their own distribution systems independently. DWM does not regulate, maintain, or hold liability for infrastructure beyond those delivery points. Residents of suburban Cook County communities — including those served by Cook County Health or collar-county utilities — fall outside DWM's retail service scope entirely. The /index for this reference site provides orientation to the broader Chicago metro governance structure and agency landscape.

References

• City of Chicago, Department of Water Management
• U.S. Environmental Protection Agency, Safe Drinking Water Act
• U.S. EPA, Lead and Copper Rule
• Illinois Environmental Protection Agency
• Metropolitan Water Reclamation District of Greater Chicago
• Infrastructure Investment and Jobs Act, Pub. L. 117-58 (Congress.gov)
• American Water Works Association
• Illinois Compiled Statutes, Metropolitan Water Reclamation District Act (70 ILCS 2605/)