A district council spokesperson said Selwyn was the first council in the country to apply for an exemption.
"The district council is continuing to work through the process of applying for exemptions using a risk-based approach," they said.
"Chlorination has been widely and safely used to treat water supplies around the world for more than 100 years, including the majority of water supplies in New Zealand."
Heather Morton, spokeswoman for cleanwaterselwyn, said many people in the district believe there has been a lack of public consultation.
"There are some areas of Selwyn with permanent chlorination already in place.
"But for areas which are not currently chlorinated many residents want to keep their precious natural resource pure," Morton said.
The group has an online petition at change.org calling for chlorine not to be added to the district's water supplies. It had over 1400 signatures as of Monday.
Meanwhile, residents wanting to receive a reminder text or email when chlorination is due to begin on their supply can sign up for alerts at selwyn.govt.nz/wateralerts.
Chlorination starts in:
Darfield – September 12
Lake Coleridge – September 19
Dunsandel – September 26
Springston – October 3
Rolleston – October 17
Rakaia Huts – October 25
West Melton – October 31
Lincoln – November 7
Taumutu – November 14
Leeston – November 21
Prebbleton – November 28
Jowers Rd – December 5
For more information see selwyn.govt.nz/water-chlorination
- starnews.co.nz