Thermal Expansion

How to prevent damage to your water heater
Thermal expansion—or the expansion of water as it is heated—occurs in all water heating systems. If there is not room for the water to expand, leaks or damage to your water heater may result. All new water meters installed by Charleston Water System are required to include back-flow prevention devices, which prevent water in your home's water pipes from being “sucked” back into the public water system. This protects the water system from contamination and helps ensure water quality, but it also eliminates a source of relief for thermal expansion, as heated water cannot expand back into the public water system.

If your water heater is not equipped with a thermal expansion relief device, the temperature and pressure relief valve (T&P valve) may leak, or in more extreme cases, serious damage to your water heater and plumbing system may result.

There are several devices available at most plumbing supply stores that will prevent thermal expansion leaks/damage. These devices are relatively inexpensive and include a thermal expansion relief valve or an expansion tank for your water heater, or a thermal expansion ball-cock for your toilet. We encourage you to consult a licensed plumber, or call our Cross Connection Control Department at (843) 727-7105, 727-6980 or 727-6981 for more information.

Please note that Charleston Water System is not responsible for leaks/damage caused by thermal expansion.