Nearly 30,000 people in the north-west of the city are now receiving unchlorinated water.
Christchurch City Council has stopped chlorine treatment at the Burnside and Farrington pump stations in the north west supply zone.
The move comes as a result of the minor remedial works the Council has done on the above ground well heads to enable them to be signed off as secure. The remaining below ground well heads have been isolated, meaning that temporary chlorination can stop.
About 80,000 people are in the North West zone and turning off treatment at the Burnside and Farrington pump stations means 37 per cent of the zone is getting untreated water.
The Council is working through a similar process to stop chlorination at the following pump stations:
The below ground wells can only stop being used at times of low (winter) water demand. If demand goes up and water needs to be drawn from the below ground well heads, water from the pump station will need to be treated.