How metal gets into tap water

Published on 05 November 2025

Council's Water Manager, Andrew Venmore, says it is a good idea to tip away the first cup of water from the tap.

"Council supplies water of the correct standard into the water main but does not control the water quality once it leaves the water main and goes into private properties' water systems."

He says most water in New Zealand is plumbsolvent, which means that if the water is left to stand for some time, such as overnight or longer, it can dissolve small amounts of metals, including copper and lead, from a building's pipework and fittings.

"Newer, better-quality fittings are likely to contain less harmful metals, but we recommend being safety conscious.

"When you first turn on the tap in the morning, run it to fill a large cup of water and tip the cup of water down the sink. This is recommended for all households, whether on public or private water supplies."

Mr Venmore says businesses, community buildings and schools should also follow this practice, particularly after periods of disuse, like after weekends and school holidays.