Maps Can Make Water Safer to Drink

By Karen Wirth

Maps are integral to our daily lives. They are the basis of exploration and navigation, helping us plot our observations to reveal new relationships and information we may have overlooked. Maps have evolved from the unwieldy foldouts to computerized maps. I use maps on a regular basis now, more commonly looking to my computer, phone or my car’s navigation system, to find my way around a traffic jam, plan a jogging route, or track the coming weekend weather. But maps can serve a more important function: they can help us protect the drinking water that is critical to our health.

EPA is harnessing the power of maps to help you and your community do just that. We have released DWMAPS—the Drinking Water Mapping Application to Protect Source Waters. This robust, online mapping tool provides the public, water system operators, state programs, and federal agencies with critical information to help them safeguard the sources of America’s drinking water.


Here are just a few ways you can use DWMAPS:

Who supplies my drinking water?

  • Perhaps you have heard that excess levels of the nutrients nitrogen and phosphorus can be in sources of drinking water. You can use DWMAPS to find out which systems serve drinking water to your county, and whether or not they face contamination issues like nutrients or fecal coliform.

Where are potential sources of contamination?

  • DWMAPS can help you trace upstream of your water supply to find potential sources of contamination. Use the map to search for waste sites, industries with recent pollution permit violations, landfills and wastewater treatment plants, sewer overflow points, pipelines, and facilities that manage carcinogenic or other toxic waste and more.

How can the Clean Water Act protect my drinking water?

  • Imagine you live near the Chesapeake Bay and learn that the Susquehanna River, a source of drinking water, is listed as “impaired” under the Clean Water Act due to high nutrient levels. You can use DWMAPS to learn more about the Susquehanna River, its tributaries, and factors leading to impairment. Then, you can participate in permit reviews or other public sessions to help your state apply Clean Water Act tools to protect it.

Is there anything else I can do?

  • Perhaps you would like to start a project to protect your local watershed. You can use DWMAPS to learn which watersheds near your home are most important to drinking water supplies. DWMAPS can also help you find partners and take action to prevent contaminants from getting into nearby drinking water sources. We’ve mapped watershed groups and drinking water contacts working around the country to restore watersheds. Link up with these groups to learn how you can get involved.

Geospatial technology is allowing us to see the world from a different perspective. Using this technology, DWMAPS brings together a suite of resources that will serve as “one stop shop” for source water protection and watershed assessment. With DWMAPS, you can now look beyond the tap and take a bird’s eye view of your drinking water. With this broader perspective, we can begin to take action together. Let’s get started

About the author:  Karen Wirth is the Source Water Protection Team Leader in the Office of Ground Water and Drinking Water.