Annual Water System Maintenance

Temporary Change in Disinfectant (March 2–30, 2026)

Annual Water System Maintenance

North Texas Municipal Water District (NTMWD) will perform its annual, temporary change in disinfectant from March 2–30, 2026. This is a normal maintenance process done each year to keep our water system clean and safe.

Why This Happens

All drinking water must be disinfected to protect public health. NTMWD normally uses a two‑step process:

  1. Ozone and chlorine disinfect the water at the treatment plant.
  2. Ammonia is added afterward to form chloramines, which help keep the water safe as it travels long distances through water pipes.

Both steps are required to prevent harmful microorganisms—such as bacteria, parasites, and viruses—from getting into our drinking water.

What Will Change

For about one month each spring, NTMWD temporarily stops adding ammonia. This means the system uses only chlorine during this period.

This is done to:

  • Clean and maintain the large water system
  • Prepare for warmer weather, which can increase the chance of bacterial growth in pipelines

Water remains safe to drink and use during this process.

This Is a Common Practice

Many water providers across Texas and the U.S. do this same type of maintenance.
NTMWD has performed this process for over 15 years while maintaining high water quality.

NTMWD and the Texas Commission on Environmental Quality (TCEQ) continue to test the water throughout the process, and the results are publicly available.

What You May Notice

During this temporary change:

  • Cities may flush fire hydrants to help move water through the system.
  • Some people may notice a slight chlorine smell or taste. This is normal and temporary.

If you are sensitive to chlorine, simple steps like letting water sit in a pitcher or using a filter can help reduce the taste and odor.

More Information

Seis Lagos Utility District has summarized the Drinking Water Treatment Process from North Texas Municipal Water District in clear, everyday language.  Source for the summary above can be located at Temporary Change in Disinfectant | North Texas Municipal Water District, TX.

Frequently Asked Questions About Chlorine Conversions

Chloramine is a disinfectant used in drinking water to kill bacteria and viruses. The North Texas Municipal Water District (NTMWD) uses chloramine in its water system, which is then delivered to the Seis Lagos Utility District for distribution.

 Free chlorine is a disinfectant used in drinking water to kill bacteria and viruses. The NTMWD uses free chlorine in the water it delivers to Seis Lagos Utility District.

A free chlorine conversion temporarily switches the disinfection process from chloramines (chlorine and ammonia) to free chlorine (chlorine only) to improve long-term water quality.

A free chlorine conversion helps maintain water quality by:

  • Reducing disinfectant byproducts
  • Clearing organic matter in pipes
  • Improving taste and odor
  • Ensuring adequate disinfectant levels

Yes, free chlorine conversions are a common maintenance practice endorsed by the Environmental Protection Agency (EPA) and the Texas Commission on Environmental Quality (TCEQ).

The conversion lasts just under 30 days, after which the NTMWD returns to chloramine disinfection.

You might notice a chlorine smell during the conversion. This is normal and the water remains safe to drink, meeting all TCEQ and EPA standards.

 SLUD flushes to ensure free chlorine reaches all parts of the distribution system. Flushing will occur again when switching back to chloramine.

Most customers will not notice a drop in pressure. If it happens, it will be brief.

Flushing can stir up sediments, causing temporary cloudiness. If this occurs, run faucets until the water clears. Avoid washing clothes to prevent staining.

Maintain the same chlorine level in pool water treated with either free chlorine or chloramines. Consult pool supply stores for more information.

Remove free chlorine by boiling water, leaving water to vent, or adding lemon juice. Note these methods do not remove chloramine. Water filtration devices can also reduce chlorine levels.

 Visit the TCEQ Website.

No, the process is safe and poses no health risks. The water remains safe for all common uses.



WYLIE, TX – Jan. 31, 2026 – North Texas Municipal Water District (NTMWD) will perform its annual, temporary change in disinfectant from March 2–30, 2026. This is a normal maintenance process done each year to keep our water system clean and safe.

“Safeguarding public health and ensuring safe water is our highest priority,” said Zeke Campbell, NTMWD Director of Water Treatment and Conveyance. “Our advanced treatment processes are among the most effective available, providing the communities we serve with safe and reliable drinking water.”

Disinfection is a critical part of the water treatment process that keeps drinking water free of harmful microorganisms, such as parasites and viruses. NTMWD’s water treatment plants use a two-step disinfection process where the water is treated, and then chloramine disinfectant (chlorine + ammonia) is added to maintain the water quality as it journeys through miles of pipes to homes and businesses. During the temporary change, NTMWD suspends adding ammonia and uses chlorine only to keep the water disinfected. This temporary change helps prepare the pipes for summer, when hotter temperatures can increase the potential for bacterial growth.

“This routine, temporary adjustment in water disinfectant is essential for maintaining optimal conditions within our pipelines and ensuring year-round water quality,” said Campbell. “This standard maintenance practice does not increase chlorine levels, and the water remains safe to drink, consistently meeting or exceeding safe drinking water standards.”

According to the U.S. Environmental Protection Agency, this temporary conversion is a common practice for many water providers using chloramines for disinfection. NTMWD follows the specified guidelines set forth by the Texas Commission on Environmental Quality (TCEQ) on how public water systems disinfect drinking water.

The absence of ammonia during these few weeks may make the chlorine disinfectant more noticeable to some people. Simple steps to minimize taste, odor, or skin sensitivities include placing a pitcher of water in the refrigerator overnight or adding a slice of citrus to the water. Adding a crushed 1000 mg Vitamin C tablet to bath water will neutralize the chlorine.

NTMWD has conducted the temporary change in water disinfectant for over fifteen years and continues to meet safe drinking water standards, earning recognition from the Texas Commission on Environmental Quality (TCEQ) as a Superior Public Water System.
During the change, the communities served by NTMWD may help move the chlorine-disinfected water through the system faster by flushing water from fire hydrants. The combination of converting to chlorine disinfectant and flushing the pipes helps maintain the system and safe water year-round.

NTMWD conducts hundreds of tests daily in a state-certified laboratory to ensure water safety. Monthly and annual water quality reports are posted online, including results of tests conducted during the annual system maintenance. Customers can view this information at www.NTMWD.com/water-testing/. The TCEQ also conducts routine sampling and testing in NTMWD and city distribution systems through an independent laboratory to confirm water quality compliance with state and federal standards.

NTMWD has posted resources at www.NTMWD.com/SafeWater, including fact sheets, frequently asked questions, infographics, videos, and guidelines for questions about water quality. NTMWD also recommends that customers review the water quality information on their city or utility websites.