The Waimate District Council first warned users of the Lower Waiho and Waikakahai East rural water schemes not to drink the water on August 6, 2022, when dangerously high nitrate levels were recorded and the council restricted drinking from the tap for over a month.
A tank with safe water was installed at the Glenavy Hall for people to collect from and it is still there today.
The council planned to commission the plant midway through last year but then delayed it to the end of the year.
However, the plant is not any closer to being commissioned as a resource consent application has still not been lodged.
The council produced an options report which considered treatment options and consenting the discharges, council asset group manager Dan Mitchell said.
"There was a desire to review two options — a woodchip bioreactor for removing nitrates and an engineered wetland."
This work was ongoing, he said.
A resource consent application would not be lodged until a treatment process had been selected.
Mr Mitchell said the council continued to monitor the raw water for nitrates.
The results were consistently measuring less than half of the maximum allowable value, which is 50mg per litre.
The nitrate probe was indicating 22mg per litre on Tuesday last week.
In April, Mr Mitchell said while they had not confirmed the type of denitrification process the plant would use, it would most likely use reverse osmosis.
In August, Mr Mitchell told the lower Waitaki south coastal Canterbury zone committee "all eyes in the industry" were on the Waimate council as it worked to meet the national drinking water standards and stay within them.
He said it was not viable to remove all nitrate from the water due to high content and expense.
One of the new challenges the council was facing was the elevated calcium levels in the supply, and the highly concentrated discharge from the treatment plant also had to be resolved.
A Public Health Communication Centre briefing on nitrates last month showed many communities across Canterbury were facing increasingly difficult decisions as nitrate pollution of drinking water sources worsened. In its briefing, the centre said the primary source of nitrate pollution in Canterbury was dairy cattle.
