TriHalomethanes Can Cause a Public Relations Nightmare
A water system in the Midwest exceeded the EPA’s total trihalomethanes (TTHMs) limit and had to issue a public notice of the violation. Local news stations picked up the story, and water system managers and elected officials started getting calls from worried consumers. In almost every case, the callers wanted to know what trihalomethanes in water were, and how they got in there.
Most water consumers in the U.S. take for granted that their water is safe. They trust that when they turn on the tap, water will flow and they can safely use it. Many have no idea what disinfection byproducts are and what causes them, or why they should be worried about them.
Is Your Water Disinfection Process Threating Lives?
Trihalomethanes, or THMs, aren’t naturally occurring in water. Water does contain total organic carbons, which is any carbon-based substance. When the water is chlorinated for disinfection, those TOCs react with the chemical and create byproducts, one of which is THMs.
Water that comes from rivers and lakes, like that used in the Midwest system, tends to contain more TOCs than groundwater and therefore ends up with more THMs. Also, THM levels are hard to predict, even coming from the same source. They can vary by season, temperature, pH, time in the distribution system, the point of chlorination, treatment process, and the amount of chlorine used. Disinfected water doesn’t start out with THMs, but ends up with them through chlorination.
The Dangers of Disinfection Byproducts
The byproducts created when water is disinfected can be dangerous. In the last few decades, the EPA has set limits on total disinfection byproducts, or DBPs, in public water systems. The byproducts, including THMs in water, can cause cancer and are suspected of causing reproductive problems. Research from the National Institutes of Health shows that people are exposed to THMs by drinking water, and by using it to shower, bathe, or wash dishes by hand. So even though chlorination makes water safe to drink and use, it can create harmful byproducts.
Safe Water Starts Before Disinfection
Taking chlorine out of the water disinfection equation may not be possible, but there are other ways to decrease THMs. The best way to reduce trihalomethanes in water is to decrease TOCs at water plants, before chlorination. This can be done by reducing the pH level of the water, increasing coagulants, and in some cases using ferric coagulants instead of alum. There are also steps water treatment managers can take to reduce THMs before disinfection, such as using a non-chlorine based algaecide or bacteriacide.
Consumers, too, can reduce their exposure to THMs. The Canadian government recommends consumers use water filters containing activated carbon that’s certified to NSF Standard 53 for THM removal. Reverse osmosis units in homes also will work to remove THMs from water. Consumers aren’t powerless when it comes to THMs, even if their water system is exceeding EPA limits.
Water safety is mostly a given in the U.S., with many water consumers unaware that THMs may lurk in their tap water. But with the latest EPA rules for DBPs and technology to remove TOCs, chlorination doesn’t need to be sacrificed because it creates THMs and other DBPs.
