The Ministry of Heath has identified that some New Zealand waters are naturally acidic and can dissolve traces of metals such as lead, nickel and cadmium from plumbing materials while standing in plumbing fittings for several hours.
Recent tests have shown residents in the South Waikato District are supplied with such water. As a precaution, all households are advised to flush and discard at least half a litre of tap water each morning by running the tap for 10 seconds before using their water for drinking, food preparation or cleaning teeth.
This will wash away corrosion products that may have accumulated.
There is no health risk related to this Ministry requirement.