High nitrate levels in Canterbury's drinking water is causing concerns for locals.
A new study shows high nitrate levels are linked to an increase risk of colon cancer and other health issues.
Fish and Game say that many samples from rivers and taps tested on Saturday were up to seven times past the study's risk level.
Richard Cosgrove from Fish and Game says, "It's only been about an hour going and we've had over 30 samples done. [We've had] some really high river samples like Silverstream was 7.3. We've also had a lady from the Selwyn District she's 7.61, she's our highest."
Sue Jarvis has been drinking the water for decades.
"I did know it was going to be high, because we live in an area with lots of dairy farms. That's actually lower than last time I had it tested."
Canterbury Medical Officer of Health Dr Alistair Humphrey says, "If that were a community supply they'd be expected under the New Zealand drinking water standards to do something about a level that had reached half the MAV. The MAV (Maximum acceptable values) is 11.3 that's the point of which it becomes dangerous for small babies."
Intensive farming is largely blamed for rising nitrate levels in Canterbury.
Urban supplies are monitored daily but rural supplies and rivers are not. Public health advice is to keep an eye on it.
"Treating it is extremely expensive, taking nitrate out of drinking water can cost up to $2000 per person per year," Mr Humphrey says.
Fish and Game is using the data for it's submission on proposed changes aiming to cut nitrate levels, protect the city's drinking water and clean up rivers.
