Christchurch water ‘should be chlorinated’

Christchurch’s water should be temporarily chlorinated after it was found the city’s drinking wells may be susceptible to contamination, Canterbury’s health boss says.

The city’s drinking water is drawn from 156 wells at 56 sites.

An engineers’ assessment has raised concerns that some of the below ground well-heads (there are 103) ‘‘may not be sufficiently sealed to prevent surface groundwater contamination, particularly in heavy rainfall events’’, Mayor Lianne Dalziel said at a briefing yesterday. The discovery meant the Canterbury Water Assessor removed the city’s secure water status.

Dalziel reassured the public that water remains safe for drinking.

She said: ‘‘There is no impact on our groundwater, that is not the issue.’’

Canterbury medical officer of health Dr Alistair Humphrey said that because ‘‘there are are no barriers to contamination in Christchurch’’ a barrier must be put in place – and said ‘‘temporary chlorination’’ should take place.

Dalziel said the city lost its secure status on December 22 after engineers looked at about 25-30 wells and could not give ‘‘secure status’’ to them.

When pressed by reporters on why the council waited a month to make the information public, Dalziel said the engineers’ report had come through about 3pm on what was effectively the organisation’s last day of work before the summer holidays – and because the drinking water risk had not changed.

Dalziel learned of it upon returning to work last Monday, January 15, she said.

Councillors were informed about the situation at a meeting last week.

Humphrey said there was no danger to public health in the last month.

Councillors will vote on the recommendations at a meeting on Thursday – including whether to temporarily chlorinate the water supply and for how long.

Humphrey said he would ‘‘be concerned’’ if his advice was not approved.

Dalziel said as soon as the council secured the below ground wellheads, the city’s ‘‘secure status’’ could be reinstated.

Thursday’s meeting was originally to be held in secret, but would now be a public debate.

Cr Mike Davidson said he would wait until Thursday’s meeting to decide whether he favoured temporary chlorination.

‘‘The drinking water in Christchurch is exactly the same as it has been for some time.

‘‘Does the changing of one word from provisional to unsecured mean we have to chlorinate our water until we get that secured status back? Because the risk hasn’t actually changed.’’

He was disappointed it took nearly four weeks to be told about the changed water status.

Cr Pauline Cotter said she would keep ‘‘an open mind and listen to all sides’’.

‘‘Personally, from my heart, I do not want to put anything in our beautiful water.

‘‘At the same time I don’t want to be responsible for a possible crisis and people being sick and even dying.’’

She understood the delay in making the information public was ‘‘inadvertent, it was not deliberately withheld’’.

‘‘The 22nd of December was a Friday ... I think the email arrived – I’m not sure who it went to, either the [chief executive] or the manager of waterways – ... about 3.30pm-4pm on Friday.’’

‘‘That hit council pretty much on Christmas Eve. That’s the question on my mind – why did it arrive at that time?’’

‘‘We’ve been aware of it now for less than a week and we’ve acted on it in the most transparent way we can.’’

Dalziel said the council was ‘‘taking every step to return to secure status as soon as we possibly can’’.

The Havelock North gastro outbreak in August 2016 made 5500 of the town’s 14,000 residents ill with the bacterial infection campylobacteriosis. It left 45 people in hospital and has been linked to three deaths.

The contamination was found to have entered the town’s drinking water bores.