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What is the Impervious Surface for My Property?

The DWSD Parcel Viewer allows you to search for parcel information by address. Impervious surface area (e.g., roofs, driveways, parking lots, decks) is used to calculate drainage charges (customers who are not on the impervious acreage rate will begin transitioning within the next year). Open the parcel viewer and type your street address with your zip code. DWSD uses data from the City of Detroit Assessor's Office and flyover images to determine the impervious surface for stormwater and snowmelt runoff. If you disagree with the data, please complete the drainage survey form.


Each year, billions of gallons of stormwater runoff and snowmelt flow from roofs, sidewalks, parking lots and similar hard, impervious surfaces into the city’s combined sewer system. This drainage, composed of water, other liquids, dirt and debris, flows into the same underground pipe as unsanitary wastewater and must be treated at the wastewater treatment plant before it can be released back into the environment. Transporting and treating this drainage costs the Detroit Water and Sewerage Department (DWSD) more than $151 million annually.

Federal and State regulatory mandates required DWSD to invest more than $1 billion in combined sewer overflow control facilities to help prevent untreated overflows and preserve Detroit’s water quality. The combination of this investment plus drainage treatment costs account for the drainage charge. This charge covers the costs for the capital, operations and maintenance associated with Detroit’s combined sewer overflow facilities as well as treating wet weather flows at the wastewater treatment plant. Drainage charges are applied on all parcels of real property within the city that drain into the city’s combined sewer system.

Since 1975, most DWSD customers have been paying for drainage as part of your water and sewer bills. Together with the City Assessor’s Office, DWSD is working to ensure all parcels that drain to the city’s combined sewer system are billed for their fair share of drainage costs.

DWSD launched a credit program in October 2016. Customers who reduce the peak flow and volume of storm water runoff on their property – by planting rain gardens or installing pervious pavement, for example – can earn credits to be applied to your bill. DWSD, in collaboration with local non-profit organizations, will offer implementation assistance to property owners and developers.

Every Detroiter shares the benefits of clean waterways, and the responsibility of managing drainage. Equitable and accurate billing, together with a citywide embrace of Green Infrastructure practices, will help Detroit become one of the “greenest” cities in America.




DWSD hosts Drainage Charge Credit Workshops.


Customer Meetings