Why Nitrates in Canterbury Water Are a Growing Concern.
Nitrate contamination in Canterbury’s drinking water is one of the most talked-about environmental and health issues in New Zealand today. With increasing agricultural activity and land use intensification, nitrate levels in groundwater—especially in rural and bore water supplies—are rising across the region.
Recent data shows:
Up to 62% of monitored sites show increasing nitrate levels
Around 10% of wells exceed the NZ drinking water limit (MAV)
Canterbury is considered the most affected region in NZ for nitrate contamination
For homeowners, farmers, and families relying on private bores, this is not just an environmental issue—it’s a direct health concern.
What Are Nitrates and How Do They Get Into Water?
Nitrates (NO₃) are naturally occurring compounds, but elevated levels in drinking water are mainly caused by:
Dairy farming and animal waste
Nitrogen fertilisers
Septic tanks and wastewater systems
Industrial runoff
In Canterbury, intensive dairy farming is the primary contributor to nitrate contamination in groundwater.
These nitrates leach through soil and into aquifers, especially after rainfall, meaning even clear-looking water can be contaminated.
Health Risks of Nitrates in Drinking Water.
Risks for Babies (Blue Baby Syndrome)
High nitrate levels can reduce oxygen in infants’ blood, causing methemoglobinemia, also known as “blue baby syndrome.”
Water above the NZ limit should NOT be used for infant formula
Pregnancy & Birth Risks
Emerging research suggests that nitrate levels:
Above 5 mg/L may increase risk of preterm birth
Could contribute to low birth weight and complications
Long-Term Health Concerns
There is growing scientific concern linking nitrates to:
Certain cancers
Thyroid issues
Cardiovascular effects
Even levels below the legal limit are now being questioned by health experts.
What Is the Safe Level of Nitrate in NZ?
New Zealand Drinking Water Standards (NZDWS):
11.3 mg/L (NO₃-N)
50 mg/L (NO₃)
However, many experts believe this level may be too high for long-term health protection.
Why Canterbury Is Especially Affected.
Canterbury has unique factors that increase nitrate risk:
Highly permeable soils (nitrates travel easily)
Extensive irrigation systems
Large dairy herd growth (10x increase since 1990)
Over 20,000 households rely on private water supplies
Shallow wells (common on lifestyle blocks and farms) are most at risk.
Does Boiling or Standard Filters Remove Nitrates?
This is critical for customers to understand:
Boiling water does NOT remove nitrates
Standard carbon filters do NOT remove nitrates
This is where many households are unknowingly exposed.
How to Remove Nitrates from Drinking Water
The only effective solutions are:
Reverse Osmosis (RO) Systems
Removes up to 95–99% of nitrates
Ideal for drinking water (kitchen use)
Compact under-bench systems
Ion Exchange Systems
Whole-house or targeted treatment
Specifically designed to remove nitrates
These are the only proven treatment barriers for nitrate removal.
Signs Your Water May Have High Nitrates
You are on a bore, well, or rural supply
Located in Mid Canterbury, Selwyn, Waimate, Ashburton
Nearby dairy farming or irrigation
Water tastes normal (nitrates are invisible and tasteless)
Testing is the only way to know
What You Should Do Next
If you live in Canterbury, especially on a private supply:
Test your water annually
Review your nitrate levels
Install certified treatment if required
Why Choose Filtration Canterbury
At Filtration Canterbury, we specialise in:
Nitrate testing and clear reporting
Reverse osmosis and nitrate-specific systems
Whole-house and point-of-use solutions
Systems aligned with NZ Drinking Water Standards
Local expertise in Canterbury water conditions
We design systems that are:
Fit-for-purpose
Cost-effective
Compliant with NZDWS and Water Safety Plans
Concerned about nitrates in your water?
Get your water tested and treated by local specialists.
Book your water test today
Freephone: 0508 FILTER (0508 345837)
admin@filtrationcanterbury.co.nz