The roll-out of the temporary chlorination programme is almost complete, with chlorine due to be added to the final water supply zones next week and Wainui at the end of the month.
This week the water supply in the city’s largest zone – the central zone, which stretches from New Brighton through Sydenham to St Albans and Papanui was chlorinated.
Next week it is the turn of the Ferrymead and Lyttelton zones to have chlorine temporarily added to their water.
The Ferrymead zone stretches from Woolston east to Taylors Mistake and supplies 8500 properties. The Lyttelton zone supplies about 3000 properties in Lyttelton, Governors Bay and Diamond Harbour.
Once the Ferrymead, Lyttelton and Wainui zones are chlorinated, the roll-out of the temporary chlorination programme will be complete.
“We began the roll-out on 26 March and it has largely gone according to plan. While we have fielded some complaints about the taste and smell of the water, it seems that most people have noticed very little difference,’’ says Christchurch City Council City Services General Manager David Adamson.
“We are constantly monitoring chlorine levels in the network and adjusting the dosages to make sure they are at the appropriate lowest possible level.’’
In December, the Drinking Water Assessor advised the Council it no longer considered the city’s groundwater supply provisionally secure because some of the below ground well heads needed to be upgraded.
On January 25, the Council decided to temporarily treat the supply with chlorine while well head improvement work was completed.
Next Thursday the Council will consider a report which recommends it improves the security of the city’ well heads by raising them above ground wherever practicable.
Mr Adamson says converting most of the below ground wells to above ground and integrating some UV treatment into the water scheme provides the best chance of returning to an unchlorinated water supply in the long term.
“Above ground well heads offer a better safeguard against possible contamination, are easier to access for maintenance and converting them gives us a better chance of gaining an exemption should the government make treatment mandatory,’’ Mr Adamson says.