Damage to Pipes
Excessively strong chlorine solutions may corrode or otherwise damage pipes and fittings if the retention time is too long. Follow the pesticide label directions and AWWA and state and local standards for disinfecting water mains to be certain that you use proper concentrations and that you observe specified retention times and proper flushing.
The water in a main being treated can be hazardous because it contains bacte- rial organisms or because it contains high levels of chlorine. Prevent people from using water from this source until you have disinfected and flushed it properly and bacteriological testing assures that it is safe.
Improper testing of the chlorine concentration of water in a main can result in inadequate disinfection. It may also fail to reveal unsafe levels of chlorine in the water after final flushing. To avoid these problems:
Be sure testing equipment is suitable for the concentration ranges being
Use only fresh chemical reagents or properly calibrated electronic devices.
Repeat the tests frequently to spot errors.
Make sure that a certified laboratory performs bacteriological testing and that the laboratory provides assurance that harmful microorganisms are not present. Use only approved sampling procedures to avoid errors in testing. Resample the water if you have any doubts about its quality.
Disposing of Water Flushed From the System
Disinfected water flushed from a main may contain high levels of chlorine that could be harmful to the environment, people, and sewage treatment operations. Contact the local county agricultural commissioner to determine if you need to make special provisions for the disposal of heavily chlorinated water. In some cases, you may need to treat the water with a reducing agent to neutralize the chlorine residual before it enters the sewage system.
DISINFECTING POTABLE WATER LINES