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Groundwater science in New Zealand

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Forty percent of people in New Zealand rely on groundwater for their drinking water, yet that water is vulnerable to contamination. 

Groundwater quality and management

Through an in-depth, research driven understanding of groundwater contamination processes, our team of groundwater scientists help clients to identify and address issues associated with landuse intensification and its effects on groundwater quality. We also design tools for water managers to enable them to assess, predict and minimise the impacts of land use, and landuse changes, on groundwater quality. 

Pesticide Survey

ESR undertakes a national assessment of pesticide in groundwater as part of a four yearly survey. 

The survey is for district and regional councils, to assess the quality of their groundwater resources. Samples are taken from approximately 165 wells and tested for a range of  over 80 pesticides.

ESR has been co-ordinating the groundwater survey since 1990.

The current survey is for the first time testing for glyphosate (the active ingredient in a popular weed killer), along with a number of Emerging Organic Contaminants (EOCs)..

ESR’s principal scientist Murray Close says glyphosate was found in only one well from the 135 wells tested – and the level detected was well below (over 400 times lower) WHO recommended health based value.

“The majority of the wells in the current survey showed no change in the amount of pesticides present compared to previous surveys with less than a quarter of the wells having low levels of pesticides detected.”

“None of the sampled wells exceeded safe drinking water standards, with most pesticides detected at less than 0.5% of the maximum acceptable value (MAV).”

Wells were also tested for the first time for a range of emerging organic contaminants (EOCs) using a highly sensitive analytical technique that measures EOCs at extremely low concentrations (parts per trillion).The survey tested for close to 30 of these compounds including a diverse range of products such as caffeine and artificial sweeteners along with pharmaceuticals such as pain relief products, contraceptive pills and sunscreen.

petone well cropped

“We found these compounds in 70 per cent of wells, and detected 25 of the 29 compounds we tested for.”

Overseas research links the discovery of EOCs in groundwater to wastewater sources including municipal treatment plants, septic tanks, farming activities, as well as indirectly from surface water.

Mr Close says there are no known health or environmental risks, however there are generally no health guidelines associated with EOCs. The contaminants are widely used and do make their way into the environment in low concentrations.”

The survey recommends that monitoring of groundwater resources is extended and that research is carried out to investigate the likely risks for the EOCs detected in this study including any impacts on ecological systems.

Results of the 2018 groundwater survey can be found here (external link)and   here [PDF, 1.5 MB]

ESR also undertake more general, ‘on-request’ assessments of regional groundwater quality for councils.

Groundwater scientists working together 

ESR, along with groundwater scientists at GNS Science(external link), Aqualinc(external link) and Lincoln Agritech(external link) are working together, building on each other’s strengths, to improve the understanding and quality of groundwater research. We call this the Groundwater Platform.


 GroundsWell Newsletters 

Read about the work of each of these organisations in GroundsWell [PDF, 4 MB], the newsletter about groundwater science in New Zealand.

[PDF, 4 MB]

Read more about ESR's water expertise.