The Mesa Water supply, like Metropolitan Water District, is treated with chloramines, a combination of chlorine and ammonia. Chloramines are effective in controlling the growth of bacteria and other microorganisms that may cause disease. Chloramines form fewer disinfection byproducts and may have no odor. People who use kidney dialysis machines may want to take special precautions and consult their physician for the appropriate type of water treatment before consumption. Customers who use fish ponds, tanks or aquaria should also make necessary adjustments in water quality treatment, as the disinfectants may be toxic to fish.