People in two coastal Otago towns are shocked at the length of time it took authorities to warn them about toxic levels of lead in their water.
Residents of Karitāne and Waikouaiti were told yesterday afternoon to stop using their tap water for drinking, cooking or preparing food.
The high levels of lead were discovered on 18 December but the alert was emailed to a Dunedin City Council (DCC) Three Waters staff member who was on holiday.
It was picked up at some point after the New Year.
The test sample had been taken on 8 December.
Authorities initially thought it might be a localised problem, but yesterday test results showed lead in the reservoir that supplies both towns.
Karitāne School Board of Trustees chairperson Jane Schofield said the water in the area had never been great, and for 12 years she had been driving to and from Dunedin in order to get drinking water.
"We have carted water from town [Dunedin] because the water is revolting here. And now to find out that it's actually not even safe to be consuming, it's just horrifying," Schofield said.
Authorities have warned residents not to boil the water, saying that does not remove lead but instead increases its concentration.
"We boil water, thinking that that's going to make it taste better," Schofield said. "But actually to find out that it concentrates the levels of lead, so we've possibly been making it worse."
The fact that the first spike in lead was detected in a sample taken on 8 December had shocked residents, she said.
"Really upset about it ... my family's probably had the least exposure because we do cart water and we have been very careful.
"I know that there are a lot of families that boil the water. They've been boiling this water for eight weeks since that first test."
The length of time it had taken for the public health warning to be issued also had Karitāne resident and local community board member Andy Barratt worried.
"It certainly is a matter of concern and the community board is working at the moment to establish all of the information that we can and clearly through the board, we would be putting those concerns back to the DCC," Barratt said.
Southern DHB medical officer of health Dr Susan Jack said initially they suspected the contamination was very localised, but that changed after new results on Monday.
"Then another test result came through just this week, which indicated a higher level at the reservoir level. So that has triggered us deciding to make it for the whole water supply until we can work out what's going on," Jack said.
The maximum accepted level of lead in drinking water is 10 micrograms per litre.
Test results show the levels to be as high as 39 micrograms per litre.
The council said the high readings are intermittent and some samples have been normal.
At the highest levels recorded, people could experience acute symptoms if consuming high levels, Jack said.
"In young children and babies, low levels don't cause any obvious illness. But higher levels can cause symptoms like vomiting or stomach pains or difficulty sleeping and low chronic levels may cause an impact on children's development."
Adults' gastrointestinal and nervous systems could be affected, and chronic lead poisoning could see mood changes, headaches, tingling, numbness, nausea and diarrhoea, or even constipation, Jack said.
Dunedin Mayor Aaron Hawkins said the lead levels were picked up when testing metals was being conducted to check the corrosivity of the water, he said.
"They were using metals as a proxy for corrosivity, in terms of coming up with asset management plans for the water supply, and because it was not for drinking water standards it was given a longer lead time in terms of processing those results, because testing for corrosion is not so time sensitive...
"When we found the results from the December testing in January, we were concerned. We took the results to the drinking water assessor at Public Health South. They weren't sufficiently concerned to advise us to stop letting people drink the water.
"Their advice was increase the frequency of your testing and keep an eye on it. We followed their advice."
While the results were known in January, people were not alerted because the council was following that advice, Hawkins said.
"We were concerned so we took it to the drinking water assessor and their advice was that it was an intermittent spike (so) increase your (testing) frequency... but they weren't sufficiently concerned to suggest that people shouldn't drink it.