When the first barrier fails: public health and policy implications of nitrate contamination of a municipal drinking water source in Aotearoa New Zealand

Safe, good-quality drinking water is a foundation of public health. Its provision relies on multiple barriers, the first being the protection of source water. Source water refers to the bodies of water (aquifers, rivers, lakes, springs, reservoirs) from which communities and individuals take their drinking water. A large waterborne campylobacter outbreak in 2016 spurred the New Zealand government to make a suite of legislative and policy reforms to strengthen the country's drinking water supply system. However, the nitrate contamination of a municipal drinking water source, and its subsequent breach of drinking water standards, should bring renewed attention to the protection of source water. This article presents a case study of the exceedance and a review of legislation and policy governing drinking water sources. It finds that while important steps have been made since 2016, weaknesses in responsibility and accountability remain in Aotearoa's drinking water supply system.