City of Plano: Toxin levels rise in some North Texas water, remain within annual regulatory limits

In the most extensive report yet, the levels of toxic byproducts detected in Plano drinking water rose substantially in March during a North Texas water supplier’s scheduled chlorine maintenance process, but remained well within levels mandated by federal regulators.

The levels of trihalomethanes—a toxic byproduct of disinfectants used by the North Texas Municipal Water District and other water suppliers—spiked in a group of Plano water samples collected on March 21 and analyzed by Allen-based Pace Analytical Services.

On average, water collected from 12 test sites throughout the city was assessed to contain trihalomethanes at levels of nearly 79 parts per billion, more than three times levels tested in January. When averaged with three other samples taken at each site since July, all sites would have met the state and federal regulatory standards, which require cities to maintain annual trihalomethane levels below 80 parts per billion.