Beginning later this month, the North Texas Municipal Water District, which serves approximately 80 cities and communities in a 2,000-square-mile area across 10 counties, will conduct its annual temporary disinfectant process change, colloquially referred to as a “chlorine burnout.”
Rockwall County receives water exclusively from the NTMWD, and a significant portion of southern Hunt County is served by the district as well.
The NTMWD and countless other water authorities nationwide conduct these annual disinfectant changes ahead of warmer seasons, ostensibly to reset the system’s disinfection capabilities and free pipes of sediment buildup. When the process began last year, celebrity activist Erin Brockovich ignited a flurry of misinformation on Facebook by claiming that the process created unsafe water conditions for customers.
In reality, the chlorine burnout method is a tested technique. During normal operations, water distributed by the NTMWD is treated at its central Wylie plant using ozone and free chlorines (ionized molecules of chlorine and oxygen), and is then treated with chloramine (chlorine and ammonia) before distribution.
During the burnout, the ammonia is removed from the chloramine, allowing the higher proportion of free chlorine - a stronger disinfectant - to propagate through the system.
The removal of ammonia from the second-stage chloramine treatment means that some customers may notice an increased smell of chlorine or slight discoloration in tap water. While a nuisance and possibly worse for those with a high sensitivity to chlorine, NTMWD officials maintain that the chlorine levels are well within safe standards, and are reviewed by state and federal authorities to boot.
“We’re regulated by state and federal authorities on our water quality, including the TCEQ (Texas Commission on Environmental Quality) and the EPA (Environmental Protection Agency)” Janet Rummel, NTMWD public relations officer, said. “The NTMWD has been using this method for over a decade.”
After the Brockovich debacle last March, the TCEQ opened a formal investigation into area residents’ complaints of bad-tasting water or mysterious rashes, but the commission’s report concluded that, while “taste and odor complaints could be due to the conversion from chloramines to free chlorine,” that “field monitoring results did not indicate any violations of applicable regulations.”
Also in response to the community concern inflamed by Brockovich’s allegations, the NTMWD voluntarily upped its number of regular and rigorous tests, and this year the district will be posting daily and weekly water test reports to its website during the burnout.
Between the district’s own tests and those done by member cities and communities, the water flowing from Wylie will be tested for byproducts more than 300 times during the burnout, and tested for overall quality several hundred-thousand times over the course of the year.
“Here in Wylie our systems analyze the water leaving the plant every 15 seconds,” NTMWD water systems manager Zeke Campbell said. “It’s a very rigorous process, and we’re constantly upgrading our facilities and technology to keep the water safe for all of our customers.”
NTMWD Watershed Manager Galen Roberts stressed the district’s priority of keeping water, at every point from purification to customers’ taps, safe for use.
“Our families drink this water every day, so we take this very seriously,” Roberts said. “What do you think is in my cup today?”
During the month-long burnout, actual chlorine levels in tap water will remain exactly the same as they are year-round, in a range from 3.8 to 4 parts-per-million, but the absence of ammonia makes the presence of free chlorine more noticeable.
The real concern with chlorine disinfection of drinking water is the potential for hazardous byproducts such as trihalomethane, which can form when chlorine and chloramine interact with decaying organic matter from plants, animals or people.
While trihalomethanes are considered carcinogenic, the substance is heavily regulated by the EPA. Water distributors are restricted to an annual average of no more than 80 parts-per-billion, a level considered safe for use, and tests of NTMWD water in the last year have produced results of trihalomethanes under the acceptable threshold.
Much of the discussion following Brockovich’s attempted exposé last year centered on skin rashes, which some believed were caused by the chlorine burnout. While rashes may be common, there have been no studies by regulatory agencies or epidemiological authorities have linked chlorine-treated water (or chlorine disinfection byproducts) with topical rashes.