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Annual System Maintenance March 6 - April 3, 2023

Water disinfection is required to protect public health and keep our water safe. North Texas Municipal Water District (NTMWD) uses proven and highly effective disinfection methods to treat the water delivered to 2 million North Texans. The annual temporary change in disinfection is required to protect public health. This maintenance procedure is essential to keeping water safe as it travels across our 2,200-square-mile service area to your tap.


Disinfection is a critical part of water treatment to keep water safe. During NTMWD’s normal water treatment processes, disinfection is a two-step process. First, it treats the water at the plant and adds disinfectant to maintain water quality as it travels long distances through pipes to homes and businesses. Both steps are needed to keep tap water free of harmful microorganisms, such as parasites and viruses.

NTMWD uses a combination of ozone and free chlorine (first step) to disinfect water at the treatment plant and then adds chloramine, which is chlorine + ammonia (second step), before leaving the plant. This maintains required water disinfection levels from the time it leaves the treatment plant all the way to your tap. According to the Texas Commission on Environmental Quality (TCEQ): “Treatment prior to distribution may utilize a number of different disinfectants, but a public water system is required to use either chlorine or chloramine in the distribution system.”


Each spring, for about one month, NTMWD suspends the typical use of ammonia to allow the remaining chlorine to keep the water disinfected as it travels through the system. This temporary change in disinfectant helps maintain the system and high water quality year-round. It’s essential to do this before summer because hotter temperatures can increase the potential for bacterial growth in pipes.

Common Disinfection Practice

Many water providers who use chloramine maintain their systems using this same process. NTMWD has been doing this for over 10 years, and high water quality has always been maintained.

Ongoing water testing required by the Texas Commission on Environmental Quality (TCEQ) is performed during the process and made available to the public. During the 2018 change in disinfectant, TCEQ conducted additional independent testing and confirmed that NTMWD surpassed all safe water requirements.

Learn more about why public water systems may temporarily change disinfectant from the TCEQ.