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1. I received a letter saying my annual backflow test is due. What do I need to do?

Contact a Backflow Tester from our List of Approved Backflow Testers and schedule a test. Provide a copy of the letter to your Tester. After completing the test, the Tester will submit the results to Charleston Water System.

2. I'm a renter, why did I receive a letter about the backflow preventer?

Compliance with our backflow requirements is the responsibility of the water account holder. If you are renting a home or commercial space, your landlord or property management company may agree to take care of the backflow installation and/or annual testing, but it is the ultimately the account holder's responsibility.

3. I received a letter saying I need to install a backflow preventer. How do I do that?

We recommend contacting a licensed plumber. You can install it yourself, but it must be installed according to our specifications, and we will inspect it after installation.

If you hire someone to install it, provide him with a copy of the letter and installation guidelines enclosed in the letter.

Once it's installed, you or the installer should contact us to request an inspection. If it passes inspection, the final step is to have it tested by a tester from our List of Approved Backflow Testers.

4. Why are backflow preventers tested annually?

Backflow prevention assemblies have internal seals, springs, and moving parts that are susceptible to wear and failure. Annual testing ensures they are functioning properly and protecting our public water system.

5. Do Backflow Testers work for Charleston Water System?

No, they are independent private contractors. Charleston Water System does not install or test backflow preventers. We only inspect them.

We do require backflow tests to be performed by Testers on our List of Approved Backflow Testers.

6. Who should I contact for more information?

Contact our Cross-Connection Control Program by calling (843) 727-7148 or send us an email.

7. How do I know if I need to install a backflow preventer?

Residential customers are only required to install a backflow preventer if the home has an in-ground irrigation system or pool. It is the customer's responsibility to notify us if an irrigation system or pool is installed.

Backflow requirements vary for commercial customers based on the business's water use. Our staff reviews newly established commercial water accounts to assess the degree of backflow hazard and notifies businesses about backflow requirements.

8. What is backflow?

Backflow is the reversal of the normal flow of water. It's caused by pressure differences and can allow contaminants from an irrigation system, boiler, or other source to enter a home or building's plumbing system or the public water supply.

Backflow prevention devices protect plumbing systems and our public water supply by preventing backflow.

9. What is a cross connection?

A cross connection is a link between a potable water system and a non-potable water system, in our case, Charleston Water’s public water lines and our customers’ private plumbing systems. Backflow can occur through cross connections.

10. What causes backflow?

A sudden drop in water pressure in our public system can cause backflow.

Backpressure can also cause backflow. Backpressure occurs when a building's plumbing system has higher pressure than the public water supply.

Both situations can allow water and contaminants from a private plumbing system to reverse flow into the public supply, potentially contaminating the water for other users. Backflow preventers keep this from happening.

11. How does Charleston Water System prevent backflow?

Since 1985, we have installed residential dual check valves on every residential water service. We also require a customers whose water use presents a backflow hazard to install and annually test a backflow prevention assembly according to our specifications.

12. What can I do to protect my home plumbing system from backflow?

Install a hose-bib vacuum breaker on each of your outside water spigots. These devices will prevent water from being back-siphoned from a hose or irrigation system into your home's plumbing.

Hose-bib vacuum breakers are inexpensive and available at hardware stores. They have been required by the Standard Plumbing Code since 1963.

13. What is the backflow administration fee?

This annual fee is assessed on each backflow prevention assembly to offset the cost of maintaining our backflow prevention program. Residential irrigation customers are exempt from this fee.

14. A backflow preventer was already installed when I moved into this home / commercial space, but I don't think I need it. What should I do?

Different customers present different backflow hazards, even at the same location. If your water use is different from the last customer, contact us to schedule an assessment.

15. I don’t use my irrigation system. Do I still have to test and maintain my backflow preventer?

As long as the irrigation system is connected to your plumbing system, the potential for
backflow exists, and you must comply with all backflow requirements, including having it tested annually.

To eliminate these backflow requirements, the irrigation system must be physically disconnected from your plumbing system.

If your irrigation system is served by the same water service that serves your home or business, you can have the irrigation system cut and capped. Once this is complete, contact us to schedule an inspection.

If your irrigation system is served by a separate irrigation meter, contact us to close the account and we will lock or remove the meter.