Wilmington DE Department of Public Works
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Frequently Asked Questions

Below you will find information that might help you understand how to find things or learn about information you might need to know about your city or town.

Wastewater and Stormwater

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  • When water goes down the drain or you flush the toilet, it enters the sanitary sewer system. From there, it travels through a network of pipes to a wastewater treatment plant, where it undergoes several processes to remove contaminants. After being properly treated, the cleaned water is safely returned to local waterways or sometimes reused for other purposes, ensuring environmental protection and public health.

    Wastewater

    Wastewater and Stormwater
  • A Combined Sewer Overflow (CSO) system means that the City’s sewer system handles both stormwater (from rain or snowmelt) and wastewater (from homes and businesses) in the same set of pipes. During heavy rainfall, the system can sometimes exceed its capacity, causing a mixture of stormwater and wastewater to overflow directly into nearby rivers or waterways. This is designed to prevent sewer backups into homes or streets, but the City works to minimize these overflows through infrastructure improvements and other measures.

    Combined Sewer Overflow

    Wastewater and Stormwater
  • Green Infrastructure or nature-based stormwater management, refers to the use of natural systems and processes to manage stormwater and reduce its impact on urban environments. This approach includes practices such as rain gardens, green roofs, permeable pavements, and tree canopies, which help absorb, filter, and slow down stormwater. By mimicking natural hydrological processes, these methods reduce runoff, improve water quality, and enhance urban green spaces, contributing to healthier ecosystems and more resilient communities.

    Wetlands Storm Drain

    Wastewater and Stormwater
  • Sewers are regulated through a combination of local, state, and federal regulations aimed at protecting rivers and streams. The City ensures compliance with these regulations by implementing and monitoring wastewater treatment processes, maintaining and upgrading sewer infrastructure to prevent leaks and overflows, and conducting regular inspections. Additionally, the City enforces permits that control the discharge of pollutants into the sewer system and manages combined sewer overflow (CSO) systems to reduce the impact on waterways during heavy rainfall. These measures help to safeguard the quality of rivers and streams from contamination.

    Wastewater and Stormwater
  • Wastewater and Stormwater
  • If you see someone dumping substances into storm drains, it’s important to report it to the City’s Public Works Department as soon as possible by calling 311. Contact Us.

    Contaminants entering storm drains can harm local waterways and wildlife. Provide as much information as possible, such as the location, description of the materials being dumped, and any identifying details about the individuals involved. Your report helps the City take appropriate action to prevent pollution and protect the environment.

    Wastewater and Stormwater
  1. Wilmington Water Utility home page

Contact Us

  1. Department of Public Works

  2. Louis L. Redding City/County Building

  3. 800 N. French Street, 6th Floor

  4. Wilmington, Delaware 19801

Hours

  1. Monday through Friday

  2. 8:30 am to 4:30 pm


  3. Dial 311 within city limits

  4. or 302-576-2620 from outside city limits

After Hours

  1. Phone: Wilmington 311 or call 302-576-2620 (outside City limits)
    After hours call 302-654-5151

  2. Email: Water (General) or Water Quality Lab

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