Plumbosolvency

The Team from Wellington Water

Did you know the Ministry of Health Drinking Water Standards recommend that you flush a mugful of water from your drinking-water tap each morning before use?

This is because all waters are plumbosolvent, which means they can dissolve very small amounts of metals if they come into contact with them.

Upper Hutt, Lower Hutt, Porirua and Wellington drinking water is described as ‘soft’ water, because there is less calcium and magnesium content. Soft water is slightly more acidic than hard water, and as a result it dissolves metals more easily/quickly.

In New Zealand, the plumbing materials/fittings (i.e. your taps) which come in to contact with water are usually the source of heavy metals, such as lead, nickel, cadmium, copper and antimony.

When you turn a fitting off there may be a small amount of water left sitting in it. Whilst our treatment processes adjust the pH to reduce the water’s aggressiveness on pipework, there is the potential that water sitting in a plumbing fitting, if unused for several hours, may accumulate minute traces of metals.

Although the health risk is small, the Ministry of Health drinking water standards 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.

For further information you can contact the Drinking Water Assessment Unit of the Wellington Regional Public Health Service, phone 04 570 9002.