The council yesterday said results from tests showed the raw, untreated water that was accidentally released from the Ross Creek Reservoir into the city’s drinking water network on Monday was, at worst, within swimming water standards, and not likely to cause illness.
Chief executive Sue Bidrose said this morning people needed to continue boiling water if they were in one of the affected parts of the central city, Leith Valley, Woodhaugh or the tertiary precinct.
"We’ve had encouraging results so far and hopefully today we will get 'day three' clear bacteria results on the water in the network."
"Today, we are also expecting a further test result for the Ross Creek reservoir water, which will tell us whether protozoa such as cryptosporidium were in the untreated water that went into the pipes earlier in the week.
"If both tests today are clear, we can lift the boil water notice."
Dr Bidrose emphasised it was important people continued boiling their drinking water or used water tanker supplies until advised the notice was lifted.
"We’ll be advising people today how to flush the pipes on their properties once the boil water notice is lifted."
The Southern District Health Board (SDHB) said the risk of contracting gastroenteritis was low.
Public Health South’s monitoring of gastroenteritis showed there had not been an increase in the Dunedin area.
Dr Bidrose said staff in charge of the network were usually "very proud" of the city’s water.
"They know they’ve caused inconvenience, and the thought that they would cause illness is against everything we stand for.
"This is a terrible thing. We’re very relieved to date nobody has been sick from the event."
On Tuesday it was confirmed millions of litres of raw, untreated water released from the Ross Creek Reservoir had entered the city’s drinking water network through a pipe previously thought to be decommissioned.
The council shut down the flow about 10am on Tuesday.
The council then issued a boil water notice covering a large swath of the inner city and north end, dispatched freshwater tankers, and began flushing the network.
Infrastructure and networks general manager Ruth Stokes said yesterday afternoon more tests had been returned that showed water was within safe drinking limits.
The council had flushed 3.5 million litres through the network, and was waiting for more results.
"We are hopeful that with the results we’ve had we’ll be in a position to lift the boil water notice tomorrow."
The connection to the pipe at the centre of the problem had been "physically severed".
"There is no opportunity for this to happen again."
Staff were checking the network to make sure any other such pipes discovered were disconnected.Dr Bidrose said water in the reservoir itself had also been tested.
Four samples were taken in north, south, east and west corners of the reservoir.
Three results came back with "very, very low" levels of coliform bacteria.
One test came back higher, though it was within New Zealand swimming water standards, Dr Bidrose said.
If people drank the water before the boil water notice, and that would have had a "brown, dirty" colour, they would have been drinking water within swimming water standards.
While it was not recommended people drink out of streams "there’s nothing excessively worrying or unusual about this Ross Creek reservoir".
Water tankers would remain in place until the boil water notice was lifted.
Dr Bidrose said the council was working through the guidelines for payouts of the $100,000 set aside for businesses affected by the problem.
Emerson’s Brewery manager Chris O’Leary said it was hoped production might resume today.
However, potential customer growth would be limited next month by the lost productivity from this week.
The loss of productivity could cost the company as much as $60,000, though that number was based on "gut feel".
Reports the company had to dump stock were incorrect, as Monday’s and Tuesday’s output remained in quarantine until the results of testing.
A Lion spokeswoman said the use of the tap at Speight’s Brewery in Rattray St had been greater than normal since the boil water notice was issued.
While she could not provide exact volumes, she said: "Anecdotally there’s been a notable increase".
