

Do you know if anything is done in town supply water to remove nitrates, or do they just aim to use water sources that are less affected?
We would need some transparency on which “suppliers” have had high readings. One would think that data would be readily available given that the suppliers are supposed to collect the data and report it. All I can find are aggregate data reports, at least from Taumata Arowai.
Here is the part of the Water Services Act 2021 where it says:
A drinking water supplier must report the results of the supplier’s source water quality monitoring to the Water Services Authority, and the Water Services Authority must provide regional councils with monitoring results annually.
Having the producers check their own work can create measurement bias. Yeah, the testing happens via accredited labs but think of the case where a single unelected person can decide to time collections around weather events to obtain more desirable results.
The long and boring “Factsheet: Drinking Water Regulation Report 2024 and Network Environmental Performance Report 2023/24” points our that:
Nitrate is an emerging risk in some parts of New Zealand.
I can’t find any consistent raw measurement data on Taumata Arowai’s web site. It looks like the 2023 data had median nitrate concentrations per supply (seems to be median for the year) but they’ve further aggregated / obfuscated that in the 2024 data.
My guess is that the data is a mess with a bunch of missing measurements and they are embarrassed to make it public. It doesn’t seem like a scandal so much as just slow uptake. Their most recent annual report boasts increases in reporting compliance.
AFAICT, an OIA would be required to get a jumble of messy data; and then, likely, a weekend to make sense of it all. You might be able to see some outliers pretty quickly though.
If your water comes from a lake / river, or is pumped up from a valley with upstream agriculture, then you probably want to check the measurement data. For my town, there’s a catchment up in the hills that feeds the towns water supply. Less than 100km away, they are pumping ground water out of a bore at the base of a valley with a high level of agriculture. Even the old measurements from the Greenpeace Map show the difference in testing levels between those two setups. The catchment in the hills has low / barely any; while the valley shows elevated levels. That jives with the explanation from LAWA on “How does nitrate enter groundwater?”.















Like when MBIE tested for herbicide / pesticide residuals in food, and then it came back too high, and then ten years went by where they didn’t publish any new testing numbers, and then they tried to increase the limit of some by 100-fold, and then thousands of people submitted on it?