Miljøprojekt, 1100 – Metalafgivelse til drikkevand, Del 3

Metalafgivelse til drikkevand, Del 3

Summary and conclusions

In this project metal release has been investigated from materials commonly used in domestic water installations. The materials tested were hot-dip galvanized steel, copper and various copper alloys. The tested copper alloys were gun metal, aß-brass and dezincification resistant (DZR) brass.

All experiments were carried out as 12-hour stagnation tests, and the test pieces were exposed for three years.

The test rig was situated at Lysholt waterworks, with medium hard water.

The experiments performed are reasonably representative for the conditions in drinking water installations. In practice, there is much variation.

The continued investigations of metal release show the same tendencies as the previous experiments.

Copper release from copper pipes and zinc release from hot-dip galvanized steel pipes tested in Lysholt were below the limits laid down in the statutory order from the Danish Ministry of the Environment (Bekendtgørelse no. 871, 21. September 2001), which was not the case in previous tests on the same materials in harder waters.

The release of lead, copper and arsenic was suitably low (below limits in the statutory order from the Danish Ministry of the Environment) from the copper alloys brass, DZR brass and gun metal produced as standard test pieces and mounted in stainless steel pipes. Yet, lead release is too high in the first three months of exposure, unless the copper alloys are washed in a special cleaning process. These results are in good agreement with previously reported results. In the test rig the test piece area accounted for 15 per cent of the test pipe area.

The nickel release from brass and DZR brass was low. The gun metal tested had a high nickel content of 1.1 per cent. The nickel release from this alloy was high, but below the limits in the Danish statutory order.