Contaminants in Drinking Water in NZ
Find out what can get into tank, bore and mains water, how it can affect your health, and how to remove it.
Not sure what’s in your water? Call us to book a water test.
What’s your water supply?
New Zealand’s drinking water standards set maximum acceptable levels for contaminants. Which ones you need to watch for depends mostly on where your water comes from. Find your supply below, then click a contaminant to read our full guide.
Rainwater tank
Rain collected from your roof can pick up bird and animal droppings, insects, leaves and whatever is on the roof itself.
Usual fix: a UV water filter with sediment filtration.
Bore or spring water
Bore water often looks clear, but it can carry minerals from the ground, farm runoff and bacteria.
Usual fix: a water test first, then whole-house filtration and UV to suit.
Mains (town) water
Town water is treated to meet NZ drinking water standards, but some things can still reach your tap.
Usual fix: an under-bench or whole-house filter.
Contaminant guides
What it is, how it gets in, and how to remove it
E. coli
Bacteria
A sign of faecal contamination from birds, animals or septic tanks. Common in untreated tank and bore water.
Giardia
Parasite
A tough parasite that causes long-lasting stomach illness. It can survive in untreated tank, bore and stream water.
Campylobacter
Bacteria
The most commonly reported gut infection in New Zealand, often spread by bird and animal droppings.
Legionella
Bacteria
Bacteria that can grow in pipes, hot water systems and showerheads, and cause Legionnaires’ disease.
Fluoride
Chemical
Added to many town water supplies in New Zealand. Find out where, and how to remove it if you prefer.
PFAS
Chemical
Known as “forever chemicals” because they don’t break down, and can build up in the body over time.
Dangerous roof materials
Chemical
Some roofs, paints and flashings can leach chemicals and heavy metals into your rainwater tank.
Silica
Mineral
A natural mineral in bore and some mains water that leaves white spots and stubborn scale on glass and fixtures.
Lead
Heavy metal
Picked up from old brass taps, fittings and some roofs. Babies, children and pregnant women are most at risk.
Nitrate
Chemical
Washes off farmland into rivers and bores. A risk for bottle-fed babies, and linked to premature birth.
Iron and manganese
Mineral
Orange and black stains, a metallic taste and blocked UV systems. Common in bore water.
Hard water
Mineral
Calcium and magnesium in bore water that fur up pipes, taps and hot water cylinders.
We can also test for and treat lead from old pipes and taps, nitrates, iron and manganese, and hard water.
Not sure what’s in your water?
Let Aqua Works test it for you.
We test tank, bore and mains water through an accredited lab to find any harmful bacteria, minerals or chemicals. Then we recommend a filtration solution matched to your water, with professional installation and ongoing support across Rodney, from Mangawhai to Albany.
Book a water test
How to protect your drinking water
The right treatment depends on your water source and the contaminants present.
Common treatment methods include:
- Sediment filtration to remove particles
- Carbon filtration to improve taste and reduce certain chemicals
- UV disinfection to eliminate bacteria and parasites
- Whole-house systems designed for tank, bore, or mains supply
A water test is the best place to start. It shows exactly what’s in your water, so you get the right solution for your property. Book a water test.
Health risks of contaminated drinking water
Biological contamination can cause
• Diarrhoea
• Vomiting
• Stomach cramps
• Fever
Long-term exposure
Certain chemical contaminants may be associated with long-term health concerns depending on concentration and duration of exposure, including potential cancer risks.
Vulnerable Groups
Babies and young children, elderly individuals, and immunocompromised people may be more susceptible to waterborne illness.
Aqua Works Guarantee
At Aqua Works, we guarantee E. coli*-free drinking water that meets New Zealand drinking water standards and all legal requirements.
Applies to rainwater and bore water with the right pre-treatment, when Aqua Works installs or services your UV system and keeps servicing it at the agreed intervals (usually every 12 months). It doesn’t cover surface water from streams, rivers, dams or lakes. We can’t take responsibility if your raw water quality changes. Recommended testing: rainwater, none needed; bore water, a full routine chemical test every two years; commercial supplies, E. coli every 3 months plus a full routine chemical test every 12 months.
*E. coli-free means no active E. coli and water that passes NZ drinking water standards.
Contaminants in drinking water FAQs
What are the most common contaminants in drinking water in NZ?
In rural areas, bacteria such as E. coli and Campylobacter are common in untreated tank water. In bore water, minerals such as silica, iron or manganese may be present. Mains water may contain fluoride, silica or PFAS (forever chemicals).
Why does drinking water in NZ sometimes have contaminants?
Drinking water in New Zealand is generally considered safe, but contaminants can still be present depending on whether your water comes from a rainwater tank, a bore or the mains supply.
Contaminants in drinking water may be biological (bacteria and parasites), chemical (fluoride and PFAS), or mineral or physical (silica and sediment). Many are invisible, odourless, and tasteless, which means homeowners may not realise they are present.
In areas like Warkworth, Snells Beach, Matakana, Omaha, and the wider Rodney District, down to the Hibiscus Coast (Orewa, Silverdale, Millwater), properties rely on a mix of town supply, rain and bore water. Each source carries its own potential risks.
How do contaminants get into your drinking water in NZ?
Contaminants can enter water through:
Roof collection systems
- Bird droppings
- Organic matter
- Corrosion or roofing material leaching
Groundwater pathways
- Soil bacteria
- Agricultural runoff
- Natural mineral deposits
Municipal infrastructure
- Treatment additives
- Pipe corrosion
- Environmental contamination in source water
Even sealed systems require proper filtration and maintenance.
How can contaminants be removed from drinking water?
The right solution depends on your water source and what’s in it. Treatment may include UV systems for bacteria, carbon filters for chemicals, sediment filtration, or whole-house systems for complete protection. Aqua Works specialises in matching the correct system to your tank, bore, or mains supply, ensuring safe, reliable drinking water. Call us to talk to our water specialists.
Can rainwater tanks contain bacteria?
Yes. Without proper filtration and UV treatment, rainwater tanks can become contaminated from roof runoff, bird droppings, and organic debris entering the system. Regular maintenance and the right filtration setup are essential to ensure safe drinking water. Aqua Works can assess your tank system and recommend the appropriate filtration and UV solution to protect your household water.
Is bore water safe to drink?
Bore water can be safe, but it’s not treated like mains supply and may contain minerals, bacteria, or nitrates depending on your location. Testing is the only way to know what’s in it and if it’s safe to drink. Aqua Works can assess your bore water and install the right solution, from sediment and carbon filters to UV or mineral treatment systems, to ensure safe, reliable drinking water for your home. Call us and find the best fit!
Is mains water always safe to drink?
New Zealand’s municipal water supplies are treated to meet NZ Drinking Water Standards.
However, treatment processes focus primarily on eliminating harmful bacteria. They do not necessarily remove:
- Added fluoride
- All chemical residues
- All mineral content
- Taste or odour compounds
For this reason, some homeowners choose whole-house or under-bench filtration systems for additional peace of mind or taste improvement.
Does mains water contain fluoride in NZ?
Yes. Many municipal water supplies in New Zealand add fluoride as part of public health policy. While it meets NZ Drinking Water Standards, some homeowners prefer additional filtration. Aqua Works can install the right filtration system to reduce fluoride and improve the taste and quality of your mains water.