Backflow Requirements for Residential Customers

Residential customers are required to have a backflow preventer if you have:

  • An in-ground irrigation system
  • A separate irrigation meter
  • A dock with water service

If you plan to install an irrigation system

  1. Notify us. Contact us before you install an irrigation system.
  2. Complete a questionnaire. We’ll send you a form to complete. Based on your answers, we'll send you info about the type of backflow assembly you need.
  3. Install the backflow preventer. Be sure to install it according to our specifications. We recommend hiring a professional installer. Provide the installer with a copy of the letter and accompanying info.
  4. Inspection. Once it's installed, contact us to schedule an inspection by one of our Backflow Inspectors (if you hired an installer, he/she will contact us on your behalf). Call the Inspection Request Line at (843) 727-6981 or email
  5. Test. Contact a third-party Backflow Tester from our Approved Tester List
    to test the backflow preventer. The tester will submit the results to us.
  6. Annual Test. The backflow assembly must be tested annually by a tester from our Approved Tester List. We'll notify you by mail when it's time for your annual test.

If you already have a backflow preventer

You’re responsible for having it tested annually by a third-party Backflow Tester from our Approved Tester List. We'll notify you by mail when it’s time for your backflow test. 

Provide a copy of the reminder letter to your Backflow Tester. This will give the Tester the INFO he needs to submit the results to CWS. Testers have the forms to be submitted to CWS.