The Region : MWD Changes Its Water Disinfectant

Southern Californians who get their water from the Metropolitan Water District are now drinking a slightly different product. The MWD has replaced chlorine as its water disinfectant with chloramines. The change brings district supplies into line with federal safety standards. The Environmental Protection Agency has found that trihalomethanes (THMs), which are formed by chlorine and organic matter in water, can cause cancer in laboratory animals. “Chloramines do not tend to cause this reaction, and THMs are not as readily formed,” said Mike McGuire, water quality manager for the MWD. The change in purification method means that Southern Californians will have to pre-treat water used in ponds and tanks for tropical fish. The new method would also affect kidney dialysis treatment, but hospitals and clinics were notified of the change previously and have installed treatment methods to remove the new compound, according to the MWD.