Miscellaneous Contaminants

 

1. Lead and Copper

a. Lead

Materials that contain lead have frequently been used in the construction of water supply distribution systems, and plumbing systems in private homes and other buildings. The most commonly found materials include service lines, pipes, brass and bronze fixtures, and solders and fluxes. Lead in these materials can contaminate drinking water as a result of the corrosion that takes place when water comes into contact with those materials. Lead can cause a variety of adverse health effects in humans. At relatively low levels of exposure, these effects may include interference with red blood cell chemistry, delays in normal physical and mental development in babies and young children, slight deficits in the attention span, hearing, and learning abilities of children, and slight increases in the blood pressure of some adults. EPA's national primary drinking water regulation requires all public water systems to optimize corrosion control to minimize lead contamination resulting from the corrosion of plumbing materials. Public water systems that have lead concentrations below 15 parts per billion (ppb) in more than 90 percent of tap water samples (the EPA "action level") have optimized their corrosion control treatment. Any water system that exceeds the action level must also monitor source water to determine whether treatment to remove lead in source water is needed. Any water system that continues to exceed the action level after installation or corrosion control and/or source water treatment must eventually replace all lead service lines contributing in excess of 15 ppb of lead to drinking water. Any water system that exceeds the action level must also undertake a public education program to inform consumers of ways they can reduce their exposure to potentially high levels of lead in drinking water.

b. Copper

Copper, a reddish-brown metal, is often used to plumb residential and commercial structures that are connected to water distribution systems. Copper contaminating drinking water as a corrosion by-product occurs as the result of the corrosion of copper pipes that remain in contact with water for a prolonged period of time. Copper is an essential nutrient, but at high doses it has been shown to cause stomach and intestinal distress, liver and kidney damage, and anemia. Persons with Wilson's disease may be at a higher risk of health effects due to copper than the general public. EPA's national primary drinking water regulation require all public water systems to install optimal corrosion control to minimize copper contamination resulting from the corrosion of plumbing materials. Public water systems that have copper concentrations below 1.3 parts per million (ppm) in more than 90 percent of tap water samples (the EPA "action level") are not required to install or improve their treatment. Any water system that exceeds the action level must also monitor their source water to determine whether treatment to remove copper in source water is needed.

2. Disinfection By-Products

A wide variety of chemicals are added to drinking water to remove various contaminants. Among them are alum, iron salts, chlorine and other oxidizing agents, all of which may leave residues or potentially hazardous by-products in the finished water. In fact, the most common source of synthetic organic chemicals in treated drinking water is the interaction of chlorine or other disinfectants with the naturally occurring particles found in the water. Byproducts of treatment with chlorine include trihalomethanes and haloacetic acids. Byproducts of treatment with ozone include bromate. Byproducts of treatment with chlorine dioxide include chlorite. The Stage 1 and/or Stage 2 Disinfectants and Disinfection Byproducts Rules provide maximum contaminant levels (MCLs) for these byproducts, as well as treatment technique requirements for disinfection byproduct precursors. Also, these regulations provide maximum residual disinfectant levels (MRDLs) for chlorine and chlorine dioxide.

3. Acrylamide and Epichlorohydrin

Polymers made from epichlorohydrin and acrylamide are sometimes used in the treatment of water supplies as a flocculent to remove particulates. Epichlorohydrin and acrylamide generally gets into drinking water by improper use of these polymers. This chemical has been shown to cause cancer in laboratory animals such as rats and mice when the animals are exposed at high levels over their lifetimes. Chemicals that cause cancer in laboratory animals also may increase the risk of cancer in humans who are exposed over long periods of time. EPA has set the drinking water standard for epichlorohydrin and acrylamide using a treatment technique to reduce the risk of cancer or other adverse health effects which have been observed in laboratory animals. This treatment technique limits the amount of epichlorohydrin and acrylamide in the polymer and the amount of the polymer which may be added to drinking water as a flocculent to remove particulates. Drinking water systems which comply with this treatment technique have little to no risk and are considered safe with respect to epichlorohydrin and acrylamide.