Large California Water Authority to Switch to Chloramine for Disinfection
The Oakland, California, water supplier EBMUD (the East Bay Municipal Utility District) shortly will make a major change in the process it uses to disinfect the product it sends to its Bay Area customers. It has announced that next month it will cease the use of chlorine as its disinfectant chemical and switch to chloramine, which is a chlorine-based compound. In this way the element chlorine can still do its work, but in a more acceptable manner.
The District is making the switch, like a number of other water utilities in the U.S., to achieve improvements in the taste and odor of the water sent out into its distribution system, as well as to meet anticipated new standards called for by federal regulations
The announcement about the move observed that in recent years EBMUD has had to increase the concentration of chlorine added during and at the end of the water treatment process to comply with regulatory requirements in its piping network of 3,900 miles. But work had to be done to minimize trihalomethane (THM) formation. THMs are suspected carcinogens which can be formed when certain natural organic materials found in some raw water sources combine with chlorine in the treatment process. When chloramine is used to disinfect the water there is a much reduced potential for the production of THMs.
The change to chloramine will solve the problem created by these competing requirements and bring more benefits to District water consumers as well. Chloramine will improve the taste and odor characteristics while allowing for effective disinfection throughout the water delivery system, and greatly reducing disinfection byproducts such as THMs. Physical changes required to accomplish the addition of the new chemical included building additional facilities at the District's six water treatment plants and adding 20 water quality monitoring stations at various sites in the distribution system.
Reports indicate that about 20 percent of the public water supply systems in the U.S. are now feeding chloramine for disinfection purposes, including the Santa Clara Valley Water District, Contra Costa Water District, Alameda County Water District and Marin Municipal Water District, all of which are also in the Bay Area.