Disinfection Performance

The drinking water delivered by DC Water contains chloramines, chemical compounds made from ammonia and chlorine. Chloramine in the water will kill bacteria and most microorganisms. Therefore, the presence of chloramines in the drinking water provides protection against contamination, either from the treatment plant or from the distribution system.

As part of the Total Coliform Rule, EPA requires DC Water to collect over 200 samples a month and test for total chlorine concentration. EPA requires detection of chlorine in each sample, or greater than 0.0 mg/L total chlorine. EPA also requires water systems to maintain the annual average at or below 4.0 mg/L. The graph below displays the average concentration of those samples over the past year.

The chlorine levels will vary seasonally. The chlorine compounds do not degrade as much in the cold temperature months compared to the warm temperature months.

What We Do