The local council issued a Do Not Drink notice on Monday after nitrate levels exceeded the acceptable levels of 50 milligrams per litre of water, posing a risk to people, particularly pregnant women and babies.
Tanker water has been made available to residents, but it could be months before the tap water is drinkable for about 650 households who get their water from the lower Waihao public water supply.
Waimate District mayor Craig Rowley has put the problem down to farming in the area, and boiling the water does not help.
The drinking fountains are off limits at the small rural Glenavy School.
Principal Kate Mansfield told Checkpoint finding out the water was not drinkable was a long process.
"Two weeks ago, we did get notification from the council to say that the nitrates were getting high, but it wasn't until I had a conversation with a man who was coming out to look at our tank water.
"Nothing to do with the nitrates, he just casually mentioned that actually the levels had gone over the exceeded amount, and we didn't know."
She said the school was still waiting on a formal notification from the council about the nitrate levels.
"We should have been one of the first people that got notified. We have 135 students at our school at Glenavy and the last couple of days, the children have been drinking the water until we found out second-hand that it wasn't acceptable."
High nitrate levels were present in the area two years ago and it had been on alert for the past few years, she said.
"We had to do a little bit of teaching around what nitrates are, we've had to cover the drinking fountains.
"We've asked them to bring drink bottles to school. But of course, not every child has a bottle of water, and we sort of had to buy more bottles of water in, we've had to do a lot of things to keep our children safe."
She said a tank of water had been dropped on site at the school, but it required staff to collect and boil it.
"We have to bring it into the staffroom, for example. It needs to go into different jugs to boil because we can't use the normal water that comes out of the main water supply.
"Children who don't have drinking bottles, we have to supply with bottled water or cups, they also need to be cleaned, decontaminated and put in the dishwashers. It's a little bit more work than we would normally be doing at this time of year."
The water for the drinking fountains comes from the main water supply, so the school has put plastic bags over them to stop the children from using them.
"There's four that we've got around the different areas. We just have to do a lot of education around making sure they don't drink any water from the taps.
"It's very hot and this is part of the problem is that we're outdoors quite a bit. We're swimming in our pool, the kids are getting quite hot so we definitely need water that we can drink."
The community had had enough of the problem over the past two years, she said.
"We know what the reason is, but we just would like the council to move forward and actually make this happen quicker.
"My board chair owns a butchery shop, he's just down the road, for him, he's got to come into the Glenavy area, fill up water out of big tanks to then go back to produce things for his business. It's a real faff out there."
The nitrates were high in the area from farming, she said.
"We've got a lot of dairy farms around our local area ... we used to be able to use flood irrigation, which would then wash away all the nitrates.
"But now we've been told they can't flood irrigate anymore, so we've got to put water on our ground right by pivots. The nitrates are just staying on the land and sinking down into our water table, which then comes into our drinking water."
Mansfield said the only blessing was that they only had two weeks left of the school year.
"But this has happened prior and we had months of this of having to boil water and cart water from different positions around the school."
Two years ago, a company sponsored drink bottles for the school children.
"I did actually go to the ministry and ask them for drinking water, for bottled water, but they basically said it was up to us to provide that.
"It's just another one of our things that we have to budget for that we don't get reimbursed, we have to buy bottled water, we have to have it available.
"I just think it's a right that in New Zealand our children should be able to drink out of the drinking fountains and drink water from schools."
