Monitoring groundwater quality
Environment Waikato monitors groundwater quality at sites throughout the Region. Measures of water quality include nitrate, pesticides, bacteria (an indicator of disease-causing micro-organisms) and iron.
On this page:
Threats to our groundwater quality come from many sources and are referred to as either point (from specific locations) or non-point sources (from wider areas).
Point sources include:
- septic tanks, leaking effluent treatment ponds and landfills
- leaking underground fuel tanks and pipelines
- mines and waste tailings
- chemical storage areas and timber treatment sites
- waste disposal sites, such as offal holes.
Non-point sources include:
- pesticide and fertiliser applications
- agricultural land use
- application of wastes to land
- saltwater intrusion.
What we are measuring
Environment Waikato monitors the state of groundwater quality in the Waikato Region for:
- background condition
- nitrates
- pesticides.
Check out where we monitor pesticide and nitrate levels in the Region.
Environment Waikato also gets groundwater information from:
- community groundwater supplies
- investigations (chemical and microbial) and data provided through resource consent applications and compliance monitoring.
The table below lists the different contaminants we measure to determine groundwater quality in our Region and their maximum acceptable values (MAVs) for drinking water.
| Contaminant |
Drinking water MAV standard1 |
Principal concerns |
| Nitrate |
50 mg/l
(11.3 g/m3 as nitrate–N) |
Human health.
Nutrient enrichment of rivers and lakes |
| Arsenic |
0.01 mg/l |
Human and animal health |
| Boron |
1.4 mg/l |
Human and plant health |
Bacteria
(indicators of disease–causing micro–organisms) |
Less than 1 in 100ml of sample |
Human health |
| Pesticides |
Chemical specific |
Human and animal health |
| Hydrocarbons |
Various |
Human health and ecology |
| Synthetic organic chemicals |
Chemical specific |
Human health and ecology |
| Heavy metals |
Metal specific |
Human health and ecology |
What we have found
The most common chemical contaminants found in community water supplies with near or above the maximum acceptable values for drinking water are:
- nitrate
- arsenic
- boron
- metals produced from corroding pipes (for example, zinc and copper).
It’s natural to find high levels of arsenic and boron in geothermal areas (mainly Taupo), but nitrate contamination is the result of the way we use the land.
Find out about the levels of nitrate, microbial and pesticide contamination in the Waikato Region’s groundwater.
Check out our indicators of groundwater water quality and groundwater well construction.
Find out how to protect community sources of groundwater.
Check out the national drinking water standards on the Ministry of Health website (online publications).
Footnotes
- Ministry of Health. 2000: Drinking-Water Standards for New Zealand 2000. Ministry of Health, Wellington.