TEMPORARY CHANGE IN DISINFECTANT For one month each spring, North Texas Municipal Water District (NTMWD) temporarily suspends ammonia in the second step of disinfection, and free chlorine is used to ensure water remains disinfected as it travels to the cities they serve and on to their customers. The levels of chlorine remain similar to year-round operations. This temporary change in disinfectant helps maintain the system and high water quality year-round. NTMWD has been doing this annual maintenance for over 15 years, follows the Texas Commission on Environmental Quality (TCEQ) regulatory guidance documents, and high water quality meeting health standards has always been maintained.