Annual Chlorine Maintenance

Gulf Coast Water Authority Annual Water Disinfection

The Gulf Coast Water Authority (GCWA) will temporarily change its water disinfection process in April of each year. This annual routine maintenance practice is necessary to maintain water systems operated by GCWA and the Galveston County communities it serves. 

The temporary change from a combination of chlorine and ammonia (chloramine) to chlorine helps to prevent taste and odor problems that can occur during the hottest months of the year.  

GCWA’s Thomas Mackey Water Treatment Plant provides drinking water to a number of communities throughout Galveston County. All communities except League City, Friendswood, Seabrook and Bolivar will be included in the chlorine maintenance. 

As part of the disinfection process, municipalities and water districts will flush their systems by opening fire hydrants. Water users may notice some water discoloration or cloudiness. These conditions are harmless and temporary and should be remedied by fire hydrant flushing. The chlorine maintenance process has not been linked to any adverse health effects. 

While the levels of chlorine in the water during the temporary disinfectant change are consistent with levels found in the water throughout the year, the temporary suspension of ammonia can make the chlorine odor more noticeable. 


Owners of fish and reptiles should follow standard water treatments using products that remove both chlorine and chloramine from the water. 

Dialysis centers will continue to treat the water to remove all chemical disinfectants, including chlorine and chloramine, before the water is used for dialysis. Home dialysis users should consult their machine manufacturers for instructions on how to properly treat their water before use. Water users can contact their local municipality or water district for questions about the water system disinfection.  


GCWA is a special water district that provides water for industry, agriculture and municipalities in Brazoria, Fort Bend and Galveston counties.  Read more at and follow GCWA on Facebook and Twitter.

Graphic Chlorine Maintenance flyer
GCWA Chlorine maintenance announcement
GCWA Chlorine Maintenance flyer
Chlorine Maintenance 2023