Frequently Asked Questions

Disinfection of water is typically a two-step process. The first step is to inactivate or kill microorganisms, such as bacteria, parasites, and viruses during treatment. The second step makes sure water remains disinfected and safe for drinking as it travels long distances through pipes all the way to the tap. Most of the year, NTMWD disinfects its water using a combination of ozone and chlorine (first step) and then chloramine, which is the combination of ammonia and chlorine (second step).

Chlorine is the most widely used water disinfectant in the world. Only chlorine-based disinfectants (including chloramine) are approved by the U.S. Environmental Protection Agency (EPA) for the second step of water disinfection. According to the Texas Commission on Environmental Quality (TCEQ) (PDF): "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."

EPA requires water treatment facilities to maintain a minimum chlorine level of 0.5 milligrams per liter (mg/l)-or parts per million (ppm)-during normal operations and a maximum running average 0.5 of 4 mg/l (or 4 ppm). These levels are safe for use or consumption.

No, we use it because in conjunction with ozone and chlorine, it is the most effective disinfectant for our large regional water system. It provides long-lasting disinfection benefits with minimal disinfection by-products. In many cases, the use of chloramines is more expensive because it requires the purchase and storage of more chemicals (ammonia). It also requires additional equipment, technology, and operations.

Chlorine reacts with and kills bacteria in the system, making them harmless to humans. However, the presence of some organic matter can remain in distribution systems. This is common to all public water distribution systems. It's not that different from bacteria on uncooked food. Once bacteria on the food is killed by high temperatures, it's harmless.

The EPA requires all water providers to disinfect water to protect public health. NTMWD uses proven, common, and highly effective methods to treat the lake water that is the source of its water. According to the Water Research Foundation, approximately 45% of the U.S. population is served by public water supplies disinfected with chloramine, the process NTMWD uses during normal operations.

NTMWD has been recognized for the superior performance of its treatment facilities in doing more than what is required to meet state and federal drinking water standards by the Texas Optimization Program (TOP) run by the Texas Commission on Environmental Quality (TCEQ). The TCEQ has given NTMWD a “superior water system” rating. View more information on the TOP program.

Lake water naturally contains sediment, organic matter, and bacteria. The water goes through a proven, multi-step process to remove sediment and organic material, and eliminate bacteria and viruses. The process includes ozone, chlorine, filtering, and then adding ammonia to create monochloramine. Ozone is one of the most powerful means to treat and disinfect water.