Water regulator Taumata Arowai last week wrote to the Christchurch City Council and 26 others which do not have protection against protozoa and other parasites on some of their supplies. The Christchurch supplies alone serve more than 168,000 people. "Although the Christchurch supply is non-compliant at present the water is safe to drink," said Brent Smith from CCC’s Three Waters team.

An RNZ article with further information is linked here: Christchurch water supply safe to drink despite being non-compliant - council | RNZ News