Ever wonder how Chicago’s water system works? - Metropolitan Planning Council

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Ever wonder how Chicago’s water system works?

MPC's Josh Ellis shows a section of an old water pipe—a hollowed out tree trunk—that was recently replaced as a part of water upgrades in Chicago.

This blog post was written by MPC research assistant Alex Gilbert.

An educational video from the Field Museum explains exactly that. The video Before the Faucet, After the Flush provides a basic understanding of how we obtain our water, treat it, transport it, clean it, and dispose of it. This piece features both the world’s largest conventional water treatment plant, the James W. Jardine Plant, and the world’s largest wastewater treatment plant, the Stickney Water Reclamation Plant. These two superlatives highlight the massive scale of Chicago’s water infrastructure, an infrastructure the public rarely sees.

While most people’s interactions with water do not go beyond the faucet, massive systems are needed to provide water to the 5.5 million people served. Chicago has another treatment plant in addition to Jardine. These facilities provide an average 1.4 billion gallons of water to the City of Chicago each day. This system uses over 9,000 miles of water and sewer mains to reach all of its customers.

Such a large system is not without challenges. Aging water infrastructure causes many leaks and loss of water. Originally installed at a rate of 75 miles a year between 1880 and 1930, water mains are wearing out. Old pipes and mains can sometimes break, causing flooded basements and streets. The city’s current pipe replacement rates are aiming to replace 70 miles of water mains a year. This move alone will save up to 40,000 gallons of water a day from leakage and main breaks.

In addition to its water supply system Chicago has an extensive wastewater treatment system. Wastewater is handled by an independent government authority, the Metropolitan Water Reclamation District (MWRD). While the Stickney Water Reclamation Plant alone can handle up to 1.2 billion gallons a day, MWRD operates six other water reclamation facilities that bring total treatment capacity to over 2 billion gallons a day. MWRD maintains 554 miles of intercepting sewers and mains that serve Chicago and surrounding suburbs.

While wastewater treatment capacity is very high, it can be overwhelmed at times. Chicago uses a combined sewer system, meaning that stormwater and wastewater are handled by the same sewers and treatment plants. During large storms, it may be necessary to dump excess from the sewers into Lake Michigan. To prevent this, MWRD is overseeing the construction of a gigantic civil engineering project; the Tunnel and Reservoir Plan (TARP) will store sewer overflow until treatment plants can handle it. TARP uses large tunnels to store excess water and will have reservoirs, which, when completed, will allow storage of up to up 17.5 billion gallons. Not scheduled to be completed for another nine years, TARP already has cost more than $3 billion.

The easiest way to reduce strain on the Chicago water system is to conserve. Assist stormwater management by avoiding water intensive activities, like laundry or dish washing, while it is raining. Sounds simple, but my current conservation goal is getting my roommate to turn off the water when he brushes his teeth. How do you personally conserve water?


  1. 1. Bill Petty from United States on April 23, 2014

    This is all very interesting. The tunnels coming from the lake are a marvel. One question I have is why Chicago fluoridates the drinking water. Many studies link fluoridation to disease and lower IQs in children. Other studies have shown that there is no significant difference the number of cavaties between communities that fluoridate and those that don't.

    I would really appreciate an honest and thoughtful response to this question.

  2. 2. Ariel on April 24, 2014

    Hi Bill, thanks for your comment. Unfortunately, we can't really answer that question because we don't focus on water quality and leave it to water operator industry best practices to determine that.

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