The government’s water regulator, Taumata Arowai, has declined Christchurch City Council’s applications for chlorine exemptions.

These applications included a request for a residual disinfection exemption for the Brooklands-Kainga water zone/

The Council had initiated the process of applying for exemptions from residual disinfection (chlorination) on a zone-by-zone basis in October 2022, starting with the application for Brooklands-Kainga, considered the most likely to succeed.

However, the exemption was denied due to the absence of a bacterial treatment barrier and an inadequate backflow prevention programme.

In addition, Taumata Arowai rejected the Council’s application for an exemption from two chlorination rules for the city’s water supply.

These rules involve the requirement for continuous monitoring of chlorine levels and ensuring adequate chlorine contact time in the water to eliminate micro-organisms before consumer distribution.

The regulator had previously provided draft versions of its decisions in May, indicating likely denial, to which the Council responded with feedback.

Taumata Arowai’s Chief Executive, Allan Prangnell, briefed Councillors on the decisions, expressing the regulator’s readiness to collaborate with the Council to identify solutions.

Prangnell highlighted that the exemptions process is relatively new, and Christchurch was among the first to apply.

He suggested joint efforts to conduct high-quality research into the aquifers supplying Christchurch’s drinking water, to determine the presence of harmful micro-organisms in these sources.

Brent Smith, Head of Three Waters, acknowledged the final decision as disappointing but expected.