Water Quality & Treatment


Drinking water treated by the Gulf Coast Water Authority meets or exceeds all standards set by the federal Safe Drinking Water Act (SDWA) and its amendments. Congress initially developed the SDWA in 1974 to protect public health and ensure that drinking water provided to the public is safe. The focus of the Act was primarily aimed at treatment. Amendments to the law in 1986 and 1996 expanded the focus to include source water protection, training of operators, funding of system improvements, as well as access to public information as important parts of safe drinking water. Every public water system in the United States must comply with the SDWA.

The United States Environmental Protection Agency (US EPA) is responsible for developing regulations and standards which conform to the provisions of the SDWA. The regulations are health-based standards and protect against contaminants found in drinking water that are naturally occurring or man-made. The US EPA also oversees the enforcement of the standards by the states, tribes, and water systems. In Texas, the Texas Commission on Environmental Quality (TCEQ) makes sure that water providers in the state follow the requirements of the SDWA. The Texas Commission on Environmental Quality (TCEQ) contracts with approved laboratories to analyze our drinking water produced by the Thomas S. Mackey Water Treatment Plant.


Thomas S. Mackey Water Treatment Plant, Texas City, Texas

Thomas S. Mackey Water Treatment Plant
Texas City, Texas

Thomas S. Mackey Water Treatment Plant


Drinking water provided by Gulf Coast Water Authority (GCWA) comes from the Brazos River. The water travels across three counties through Jones and Oyster Creeks and into GCWA’s man-made canals and Industrial Reservoir before reaching the Thomas S. Mackey Water Treatment Plant.

The Mackey Water Treatment Plant, located in Texas City, Texas, is a 50 million gallon per day conventional water plant built in 1980. Improvements have been completed over the years to maintain reliability and to increase production. The plant is staffed every day, 24/7, to continually produce a high quality drinking water to a population of over 185,000.

Initial treatment begins with the application of powdered activated carbon to help eliminate odors. The water is then disinfected with chlorine dioxide. The chlorine dioxide is a powerful disinfectant that destroys bacteria and microorganisms and also reduces taste and odor.

Next, suspended particles in the water are combined together in a process called flocculation. The floc particles settle and remaining particles are removed through filtration. Our filters are composed of silica sand and granular activated carbon.

After filtration, water is treated for corrosion control and fluoride is added.

Chlorine dioxide and chloramines are added in the final process of treatment to disinfect the water and protect it as it makes its way through the transmission and distribution systems to the end-user’s tap.

The Thomas S. Mackey Water Treatment Plant staff monitors and performs water quality tests daily to ensure a high quality drinking water that meets or exceeds state and federal regulations is produced for our customers.

GCWA is a member of the American Water Works Association and Water Research Foundation. We actively participate in water quality research projects that allow us to improve our operations and treatment process.

Corrosion Control and the Flint, Michigan Water Crisis

Recently, the City of Flint, Michigan switched its water supply from the Detroit Water Dept. to its own Flint River, failing to apply corrosion control treatment to the water. The Flint River water contains high levels of chloride which accelerates corrosion to lead pipes, causing the lead to leach into the public water supply and triggering a public health emergency.

Gulf Coast Water Authority has long treated the Brazos River water with a corrosion control inhibitor called zinc orthophosphate to combat such an event from occurring.

For more information regarding the Flint, Michigan lead crisis, follow the link below:

Corrosive Chemistry: How Lead Ended Up in Flint’s Drinking Water – Scientific American from Scientific American’s Tweet