Source Water

The journey to clean tap water begins long before raw water arrives at our Hanahan Water Treatment Plant, where we work very hard every day to treat and distribute the highest quality water possible.

Water is gathered in large watersheds that eventually drain into the Edisto River and Bushy Park Reservoir from which we pull raw water to treat. The act of safeguarding the watersheds and improving the quality of the water in them is called source water protection and it is a task we’ve taken seriously for over 100 years. In fact, CWS has utilized no less than four different sources of raw water in that time and has spent millions on water quality studies, many of which have been performed by the experts at the United States Geological Survey (USGS). Links to these studies are available below.

Charleston Water System believes we have a shared responsibility to protect the environment and plays an active role in the watershed to ensure water quality is sustained, or even improved over time. We are proud to announce that we, in collaboration with Joint Base Charleston, have been granted funding to help cover costs associated with the development of a Watershed-Based Plan (WBP) for the Bushy Park Reservoir and Foster Creek Watershed. WBPs are important tools to leverage collaborative partnerships with other stakeholders in a watershed to protect and improve water quality. These plans are also important to guard against urbanization and other land development activities which could impact the quality of our source water.

USGS Water Quality Report

USGS Hydrology Report


What can you do to help protect our watershed?


  • Pick up the poop! Pet waste adds bacteria and excess nutrients, which contribute to algae growth that disrupts plants and wildlife.
  • Don’t dump into storm drains; they empty directly into a water way.
  • Properly dispose of medicines, chemicals, oils and paints. The best way to avoid improper disposal, is to only purchase chemicals you’re certain you will use.

  • Don’t over-fertilize your lawn. It washes into storm drains, streams, rivers and oceans.
How does CWS ensure the Charleston area has a plentiful source of high quality drinking water?
In 2018, a Source Water Manager position was created and filled for the purpose of source water protection and planning. This person is tasked with:

  • Maintaining source water infrastructure
  • Source water quality monitoring
  • Collaboration with stakeholders within the Santee and Edisto surface water basins
  • Serving as the point of contact for federal, state and local government agencies, and collaborating with SCDHEC, EPA, SCDNR and USGS on all aspects of water quality and watershed stewardship
  • Public outreach and education for watershed issues

More information and further resources: