DRINKING-WATER QUALITY - IMPACT OF NON-LEAD-BASED PLUMBING SOLDERS

Studies were done on the leaching of Ag, Cd, Cu, Pb, Sb, Sn and Zn from 95/5 Sn/Sb-, 96/4 Sn/Ag-, and 95.5/4.0/0.5 Sn/Cu/Ag-soldered copper coupons into high-purity, tap, treated and well water samples as a function of standing time in a static test on new plumbing. No significant leaching of Ag, Cd, Pb and Sb occurred from the above solders into the water samples. Tin was released into the water samples from all the solders. The amount of Cu released from soldered copper pipes was generally lower than that released from non-soldered copper pipes, especially in the case of treated and well water samples, due to galvanic corrosion. The amount of Zn leached was well below the Guidelines (5 mg/l) for Canadian drinking water quality. Examination of the coupon surfaces using electron microprobe and X-ray photoelectron spectroscopic techniques showed the presence of tin oxides due to galvanic corrosion.