Use Of Chlorinated Isocyanurates For Drinking Water Chlorination

In July 2001, the U. S. EPA approved OxyChem's chlorinated isocyanurates, trichloroisocyanuric acid and sodium dichloroisocyanurate (anhydrous or dihydrate), for routine treatment of drinking water. These are the first new chlorine-based disinfectants approved for drinking water use in many years. This presentation summarizes the chemical and physical properties of these materials, discusses how they are normally used, and compares their properties to the other chlorine-based products. Chlorinated isocyanurates are stable, dry solids, containing high concentrations of available chlorine, and are available in either tablet or granular form. Feeders for each form are available in various sizes, so that these materials can be used in a range of water systems, with chlorine-equivalent feed rates ranging from less than one to greater than 200 pounds per day. Since these products are solids, a spill or leak is easily contained and cleaned up. They are very stable over time, maintaining their available chlorine content almost indefinitely. They dissolve completely and do not contain calcium, and thus do not contribute to scale or sludge formation. Chlorinated isocyanurates have been used in swimming pools for over forty years, and a significant data base of toxicity information has been developed to support the EPA registrations. This data supports the conclusion that these materials are safe for treatment of potable water. A unique feature of the chlorinated isocyanurates is the presence of cyanuric acid. Cyanuric acid is not fetotoxic, teratogenic, mutagenic, or carcinogenic and does not bioaccumulate. Exposure calculations show that no more cyanuric acid is ingested via drinking water than is normally ingested during pool use. OxyChem's chlorinated isocyanurates are also certified by NSF under Standard 60.