At the tap - Plumbosolvency

All drinking water is plumbosolvent, which means it can dissolve very small amounts of metals, and our treatment processes adjust the pH to reduce the water’s aggressiveness on pipework and tapware. However, there is the potential that water sitting in a plumbing fitting, if unused for several hours, may accumulate minute traces of metals which can contain lead, nickel, cadmium, copper and antimony.

Although the health risk is negligible, we recommend that you flush a mugful of water from your drinking-water tap each morning before use. This should remove any water that was left in your fittings, and metals that may have dissolved from the plumbing fittings. All households are advised to take this precaution, whether they are on public or private water supply.

As a generalisation, soft water is deficient of minerals and slightly more acidic than hard water, which is richer in minerals and as a result it dissolves metals more quickly and easily. Upper Hutt, Lower Hutt, Porirua, Wellington and South Wairarapa drinking water is described as ‘soft’ water, because there is less calcium and magnesium content.