Annual Chlorine Maintenance

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Each year, the North Texas Municipal Water District (NTMWD) conducts chlorine maintenance on its water transmission system and customer cities’ distribution systems for a 28-day period. As a member city, Richardson receives its water from NTMWD.

The Texas Commission on Environmental Quality (TCEQ) allows water suppliers to perform chlorine maintenance in order to maintain proper chloramine levels (required by the TCEQ) during the warm weather periods, thus conserving water.

Chloramine, a combination of chlorine and ammonia, is used to disinfect water. Disinfection is a critical part of water treatment to keep water safe. It involves a two-step process that treats the water, then adds disinfectant to maintain water quality as it travels long distances through pipes to homes and businesses. Both steps are needed to eliminate and keep tap water free of harmful microorganisms, such as parasites and viruses.

Chlorine maintenance does not affect water quality, and the water remains safe for use. Consumers who are sensitive to taste and odor changes in drinking water might notice a slight change during this period, however this palatability change does not alter the quality of the drinking water.

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Why is drinking water disinfected?
Disinfection of drinking water is critical to protecting consumers from disease-causing microorganisms, called pathogens, including bacteria or viruses. Disinfectants are very effective at inactivating (or killing) pathogens and have enormously benefited public health.

What are the drinking water disinfection requirements in Texas?
Public water systems are required to disinfect water prior to its entering the distribution system that carries it through pipes for delivery to consumers. Public water systems in Texas are also required to maintain a minimum amount of residual disinfectant throughout the distribution system to make sure levels of harmful microorganisms remain low. 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.

Why does the NTMWD use chloramine?
Chloramine is an effective disinfectant and persists over a long period of time, particularly in areas with high temperatures. This makes chloramine useful in Texas’ large distribution systems, such as those of cities with numerous connections and in rural water systems with fewer connections spread out over a large geographic area.

Is chloramine safe?
Yes, water disinfected with chloramine is safe for drinking, cooking, bathing and everyday use. The EPA, the Centers for Disease Control and Prevention, and the World Health Organization have determined that chloramine is a safe disinfectant and that water disinfected with chloramine within regulatory standards has no known or expected adverse health effects.

What is a free chlorine conversion/chlorine burn?
A free chlorine conversion, also referred to as a chlorine burn, occurs when a water system that typically uses chloramine removes ammonia (needed to form chloramine) from the treatment process, and disinfects the water with only chlorine. Chlorine is more effective than chloramine at inactivating certain types of bacteria. Excess ammonia, which can accumulate in a chloramine-treated distribution system over time, is a source of food for specific types of bacteria that are harmless to people. These bacteria can make it difficult for public water systems to maintain a disinfectant residual, which means that microorganisms that are harmful to people can grow. The chlorine burn is a common practice by many public water systems throughout the country to reduce the number of the bacteria so that a satisfactory disinfectant residual can be maintained throughout the distribution system.

Why doesn’t Dallas perform a temporary change in disinfectant?
It is our understanding that the Dallas Water Utilities is able to maintain its system through a comprehensive flushing program. However, based on NTMWD’s expansive system serving nearly 80 communities across North Texas, maintenance solely through flushing is not a viable or cost-effective option for our unique regional system.

Will the water taste or smell differently during the free chlorine conversion?
Properly conducted, free chlorine conversions can often cause the water to have a different taste and/or odor than when using chloramine for disinfection. Customers will likely be able to notice the difference, but there are no health effects associated with the change in taste/odor. Once the water system has returned to using chloramine as the disinfectant, the taste/odor of the water will return to normal.

What can I do if I don’t like the chlorine taste or smell?
The closer you live to the water treatment plant, the more noticeable the chlorine odor or taste may be. Some tips include running the tap for a few minutes before using the water, refrigerating water in an open pitcher, adding a slice of citrus/ cucumber several hours before using or using a National Science Foundation (NSF/ANSI) approved water filter. Check out more tips at

Is testing done during the chlorine maintenance period?
Routine monitoring of bacteria, disinfectant residuals, nitrate, nitrite and many other parameters occurs during the maintenance period at the treatment plant and in the distribution systems. Samples are collected by TCEQ licensed water operators and analyzed in appropriately accredited laboratories. NTMWD has performed process control monitoring at its treatment plant for trihalomethanes (THMs). The results for multiple samples have been less than 28 parts per billion (ppb) which is significantly lower than the EPA Maximum Contaminant Level of 80 ppb. The results of all testing are within federal and state guidelines.

Is there any independent testing?
TCEQ conducts routine water sampling in the NTMWD and city systems through an independent laboratory to confirm water quality compliance with state and federal standards. The cities we serve also collect their own water samples, which are analyzed in NTMWD’s state-certified laboratory and reported to TCEQ.

If you wish to perform additional testing …
Use a state-certified laboratory to provide sampling instructions, containers and ensure accurate results. You can find an accredited laboratory in Texas through the link listed below. Consumers should be cautious of, and do research on, any private companies offering free testing to sell products or services.

Pool test kits are not a reliable method to test drinking water.
According to the Centers for Disease Control and Prevention (CDC), pool kits take inaccurate readings over time; do not provide reliable, quantitative results; and lack calibration and standardization. You can learn more from CDC.

Beware of claims from companies advocating filtration for water safety.
NTMWD’s water is safe to drink without filtration. Some filters can help dissipate chlorine odor, taste and skin sensitivities. Look for filters labeled with National Science Foundation (NSF/ANSI) approval. has some additional filter guidelines.

Where can I find more information?
More information about water treatment and the use of chlorine as a disinfectant, including free chlorine maintenance, can be found on the following websites:

More information about NTMWD water quality, including test results is available at

For more information about the free chlorine maintenance, please contact Denise Hickey, NTMWD Public Relations and Water Conservation Manager, at 972-442-5405.