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Control of New Copper Corrosion in High-Alkalinity Drinking Water using Orthophosphate - article
Grace, S., D. A. LYTLE, AND M. N. Goltz. Control of New Copper Corrosion in High-Alkalinity Drinking Water using Orthophosphate - article. Journal AWWA. American Water Works Association, Denver, CO, 104(1):E15-E25, (2012).
To inform the public.
Research and field experience have shown that high-alkalinity waters can be associated with elevated copper levels in drinking water. The objective of this study was to document the application of orthophosphate to the distribution system of a building with a copper problem associated with high-alkalinity source water. The alkalinity and pH of the water were 273 mg CaCO3/L and 7.4 respectively, and copper levels at taps ranged from 1.4 to 2.3 mg/L. Experimental bench-scale “jar tests” proved to be useful for establishing an appropriate orthophosphate dose. A simple chemical feed system delivered orthophosphate to the building at a dose of approximately 3 mg PO4/L. Within several weeks, copper levels throughout the building dropped below the Lead and Copper Rules copper action level of 1.3 mg/L. Orthophosphate levels remained consistent across the building and did not change during stagnation. The addition of orthophosphate also increased chlorine residuals of flushed water samples.