Christchurch's drinking water is classified as plumbosolvent, meaning it's capable of dissolving trace levels of heavy metals such as lead and copper out of some household plumbing and fittings.

Regular consumption of water containing these metals can, over a long period of time, pose a health risk.

Although the health risk is small, the Ministry of Health recommends people flush a cupful of water from their drinking-water tap each morning before use, to remove any metals that may have dissolved overnight from the plumbing or fittings.