Frequently Asked Questions

Wilmington's water primarily comes from the Brandywine Creek, which is part of the Brandywine-Christina Watershed. Originating in Chester County, Pennsylvania, the Brandywine flows through a significant portion of Delaware and is pumped from the Creek to our treatment plants. Additionally, the City owns Hoopes Reservoir and can pull water from here as a backup source. To ensure a clean and reliable water supply, the City implements various measures to protect the Brandywine watershed, including monitoring and pollution control efforts.

Water Treatment Process

1. Raw Water Intake: Water is drawn from the Brandywine Creek or Hoopes Reservoir. Large debris like branches, leaves, and trash are removed from the water.
2. Coagulation/Flocculation: Chemicals are added to the water to make small particles that stick together (coagulation) and form larger clumps (flocculation), making it easier to remove impurities.
3. Sedimentation: The water moves slowly through large tanks, allowing the heavier particles to settle to the bottom.
4. Filtration: Water passes through filters to remove remaining impurities.
5. Disinfection: Chlorine is added to kill harmful bacteria, viruses, and other pathogens.
6. Finishing Chemicals: Fluoride is added to the water to promote dental health. Zinc Orthophosphate is added to the water to prevent pipe corrosion.
7. Storage and Distribution: The treated water is stored in reservoirs or towers and then distributed to homes and businesses through a network of pipes.

Throughout the process, water quality is continuously monitored to ensure that it meets safety standards set by regulatory agencies.

Under the leadership of the U.S. Environmental Protection Agency (EPA), the Safe Drinking Water Act (SDWA) authorizes the establishment of legal limits for specific contaminants in drinking water. Read more about the EPA's Drinking Water Regulations here.

The Environmental Protection Agency (EPA) says that discolored water is safe to drink unless it's been contaminated with other substances. The EPA has made National Secondary Drinking Water Regulations (NSDWRs) that give non-mandatory standards for 15 contaminants. While the EPA doesn't make these Secondary Maximum Contaminant Levels (SMCLs) mandatory, they're set as guidelines to help public water systems manage their drinking water for things like taste, color, and smell. However, these contaminants aren't seen as risky to human health at the SMCL. Read more about the EPA's Secondary Drinking Water Standards here.

The water introduced into our system is initially clean and clear. However, many of the pipes in the City are made of unlined cast iron. Sometimes, this buildup of iron inside the pipes can be released when there's a disturbance like main breaks, construction, or fire hydrant flushing. These events may cause the water to appear rusty. Typically, this discoloration is temporary and should clear up shortly after the issue is resolved and the water is flushed out through your piping system.

If you see rusty water coming from your faucet:

1. Call the Call Center at 302-576-3878, and they will help you figure out and fix the water issue. Contacting the Call Center is the only way the City knows about a water problem. This makes an electronic record, which is especially helpful if the issue happens again.
2. Get a sample of the discolored cold water in a white cup or bowl for comparison and put it aside.
3. Go to the lowest sink in the house, set a timer for 15 minutes, and run only cold water. Running the hot water can make rusty water fill the hot water tank, which will then need to be drained.
4. After 15 minutes, get another sample in a different white cup or bowl and compare it with the first one. Keep flushing and watching for the water to lighten. If it hasn't lightened, call the Call Center again for more instructions.

Black spots or slimy buildup on faucets, drains, or showerheads are usually biofilm—a mix of naturally occurring bacteria, mold, and mildew. It forms in damp areas and feeds on soap, toothpaste, and other organic materials.

This is not harmful for most people and doesn’t mean your water is unsafe. It's caused by moisture, low light, and trapped debris—not by contamination in the water supply.

Black spots and slime are often in humid spaces, on rarely used fixtures, or in older plumbing.

To clean it, scrub the area or remove the aerator and soak it in vinegar, hydrogen peroxide, or diluted bleach. Prevent buildup by using fixtures regularly, improving ventilation, and cleaning often.

Air – Cloudiness in water, especially cold water, is caused by air in the water line. To confirm this is air, fill a clean glass with cold tap water and let it sit on the counter. Watch as the cloudiness clears gradually as the bubbles dissipate.

Lime – lime is a white powdery substance made of mostly calcium and is used to adjust the pH of the water to adequate levels. This limits its corrosion potential when traveling through metal pipes. Draining your hot water heater and cleaning faucet aerators can help eliminate lime accumulations.

Your drinking water is treated at one of two treatment plants and surpasses all requirements of the Safe Water Drinking Act, established by EPA. Therefore, filtering your tap water may not be necessary for most residents. However, it is important to note that there are old iron water mains in the city that are being replaced, which may lead to intermittent issues with rust in the water supply. Additionally, your home’s internal plumbing should be considered. 

The City of Wilmington's drinking water is treated to prevent lead contamination, but older homes may still have lead service lines.  While the lead service line may be a source of lead in the home’s plumbing, there could still be lead in a home’s interior plumbing such as faucets or fixtures. Water filters are available at hardware and home goods stores, as well as online retailers.  When choosing a filter, ensure it is rated NSF/ANSI Standard 53 for lead filtration as not all home water filters are certified to remove lead.

If your street is undergoing or scheduled for a capital improvement project—like a water main replacement or rehabilitation— lead service line replacement will occur in conjunction with that project, and you will be provided with a free water filter for 6 months by the City of Wilmington at no cost to you. Read more about our Filter / Pitcher Program here. 

A water meter measures the volume of water used in a home or business by tracking the flow through a pipe. Utilities use this data to determine billing and monitor water usage for efficient distribution. See the below information or access it here (PDF).