Requirement to boil water likely to be lifted soon
Last updated 10:14 30/03/2011
Christchurch's boil-water restrictions are about to be lifted.
Canterbury medical officer of health Alistair Humphrey said the city's water supply had been free of faecal contamination for five days and the boil-water notice would probably go "within a few days".
Residents were warned to take precautions with water used for drinking, food preparation and teeth brushing .
The Christchurch City Council has installed 26 pumps to inject chlorine into the water supply. The chemical kills water-borne bacteria and viruses that could cause diseases.
About 60 per cent of the city's households, mainly in the eastern suburbs and the central business district, have chlorinated water.
Chlorination has not been necessary for the rest of the city.
Humphrey said the last hurdle before lifting the notice was to test water in Sydenham and Phillipstown to ensure chlorine had reached the Health Ministry minimum of 0.2 milligrams of chlorine per litre of water.
"I'm looking at a map now, from a couple of days ago, that shows [E. coli levels are] clear across the city," Humphrey said.
"I think [the boil-water notice will be lifted] within a few days."
Christchurch City Council water and waste unit manager Mark Christison was more cautious.
He hoped the boil-water requirement would be lifted within a week.
Christison expected chlorination to last about six months.
Some Christchurch residents had complained of an intense chlorine smell and a soil taste in their water, prompting more people to buy bottled water.
Christison said chlorine "dosing rates" had to stabilise in some areas.
Water pipes in some suburbs were leaking heavily and the council was most concerned about the hill suburbs.
In the middle of the night, water flow in some areas was 2 1/2 times higher than usual, he said. Every Christchurch street should now be reconnected to the water network, Christison said.
In Burwood, Bexley and parts of Avonside and Dallington, water pipes had been laid above ground because the underground pipes were so damaged.
Those pipes would eventually have to be buried to normal infrastructure standards.
Humphrey said "transgressions" in the city's water supply were much worse after the devastating February 22 earthquake, compared with last September's quake.
"There weren't a lot of them, but they were in many different places," Humphrey said. "It was clear the integrity of the reticulation system had been breached. There's more work to do, but the chlorine will keep it safe for now."