Controlling corrosion in drinking water distribution systems :how Fitchburg Massachusetts is preparing for the lead and copper rule

Daley, Kathleen
Abe Bernstein
Department of Environmental Studies
1992
Lead and copper are two of the 60 drinking water contaminates that the Safe Drinking Water Act currently regulates. Corrosion within the distribution system is the major source of both of these contaminants in drinking water; therefore, regulations for them were issued together as the Final Lead and Copper Rule in June 1991. The Lead and Copper Rule establishes a National Primary Drinking Water Regulation (NPDWR) for lead and copper and requires public water systems to assess the extent of lead and copper contamination through monitoring procedures, and if necessary to install treatment to reduce the corrosivity of water. This paper describes 1) the regulation of lead and copper in drinking water, 2) sources and chemistry of lead and copper in drinking water and 3) the way Fitchburg, Massachusetts is addressing the problem of corrosion in its drinking water distribution system. The most significant finding of this research was that the sodium hydroxide/bicarbonate method of corrosion control reduced the levels of lead and copper in Fitchburg’s drinking water distribution system. Sampling conducted during 1989 and 1990 showed that the levels of lead were reduced by approximately 50% and the levels of copper were reduced by approximately 75%. Sampling conducted in 1991 indicated that Fitchburg will be able to meet the Action Levels of the lead and Copper Rule by using this method of corrosion control. This study also showed the importance of knowing the physical characteristics of the sampling sites when conducting a monitoring program for lead and copper. The most significant physical factor was the location of the sampling site within the distribution system. The sites that were on dead-ends or in areas of low flow had much higher levels of lead and copper than did sites located in areas of higher flow. When the lead and copper results from Fitchburg were compared with the results from two neighboring communities, two findings were discovered that need further research. First, the amounts and types of chlorine used to disinfect drinking water were different in each community and may have affected the corrosivity of drinking water. Second, one of the communities sampled, Leominster, Massachusetts, had significantly lower levels of lead and copper than the other two communities. The samples collected in Leominster were within a distribution system that is served by filtered water. Filtered source water may be less corrosive than unfiltered water; however, more research is needed to confirm this.

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