Two galvanic pipe-loop couples (lead-copper and lead-bronze) were exposed to controlled changes in water quality (disinfectant, pH, alkalinity, and phosphate) and monitored for changes in lead and copper release. In addition, open circuit potential profiles were measured along the junction of dissimilar metals to determine the extent of the zone affected by galvanic coupling.
Sampling results showed changes in water quality caused transient (short-lived) increases in lead and decreases in copper that corresponded to the galvanic action of lead on the other coupled metal. Open circuit potential measurements indicated that the galvanic effect on corrosion potential can induce a shift of up to 600 mV. The extent of the galvanically affected zone was limited, penetrating no more than a few inches from the juncture along the surface of each pipe. Additional testing confirmed strong effects of external versus internal coupling on the open circuit potential profiles in the galvanically affected zone.