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Drinking Water Quality

Complying with drinking water standards

Rotorua Lakes Council is committed to achieving full compliance with all applicable requirements across its water supplies, treatment plants and reticulated networks.

These are outlined in the current Water Services Act 2021 (Drinking Water Standards for New Zealand), and the Drinking Water Quality Assurance Rules 2022.

Read about our drinking water compliance - (PDF, 285KB)

Testing our water

Disinfection

In the Rotorua district, our water is extremely clean and requires little treatment. Water supplies are disinfected using chlorine treatment.

Ultraviolet treatment plants have been installed on all supplies to comply with the above standards.

Fluoridation

Rotorua Lakes Council has agreed to implement a directive to fluoridate the Rotorua Central (Karamu Takina Spring) and East (Waipa Spring) water supplies by March 2025.

Read more about fluoridation of Rotorua's water

Water hardness

Water hardness is an aesthetic quality caused by minerals in the water. Hardness is classified or measured by the concentration level of calcium carbonate. Read the factsheet below for the most recent hardness classification for Rotorua's water supplies.

Download a water hardness factsheet - (PDF, 757KB)

Troubleshooting water issues

Is your water looking, smelling or tasting different? Here are some potential causes and what to do.

Problem Cause Solution
Stale tasting, yellow/rusty brown water, stains on washing or small particles in the water
Rusting iron pipes at home or sediment in the water supply Fully run a tap for a few minutes. If the water clears, replace home pipes. If not, contact us to clean the water mains.
Metallic taste or smell Corroding pipes or fittings (plumbosolvency) Run the tap for a few minutes to flush the pipes.
Green or blue water, green stains on plumbing Corroding copper pipes or fittings Consider installing a water softener. You may also need to replace the corroded pipes.
White, cloudy or milky water Air in the water or old pipes Let it sit; the bubbles should disappear. If not, contact us to flush the water mains.
Slight smell of chlorine Chlorine in the water Not harmful; the smell should go away quickly.
Report a problem with water mains

Plumbosolvent water - notice to consumers

Many natural New Zealand waters tend to be soft with moderate to low levels of alkalinity and pH. These properties can give the water the potential to leach metals from taps and other plumbing fittings when water stands for several hours, for example overnight (ie. are plumbosolvent).

To ensure that any risk from higher levels of metals is avoided, the Drinking Water Standards of New Zealand requires that drinking water suppliers pass on to consumers the following message from the Ministry of Health.

"Although the health risk is small, the Ministry of Health recommends that you flush a mugful of water from the tap each morning before use to remove any metals that may have dissolved from the plumbing fittings."

Drinking water testing at the Environmental Laboratory

What’s in our water?

A typical analysis of the chemical makeup of the Rotorua district water (2020 - 2025), prior to treatment, can be found in the following table.

Chemical Drinking water standard limits (if assigned) Reporoa source - Wharepapa Reporoa source -Deep Creek Kaharoa (& Hamurana) source Mamaku Bore 4 source Mamaku Bore 6 source
pH N/Z 6.6 6.9 6.6 6.1 6.2
Nitrate-N 11.3 0.58 0.69 0.82 1.95 1.40
Phosphorus N/A 0.09 0.09 0.10 0.06 0.05
Arsenic 0.01 <0.005 <0.005 <0.005 <0.005 <0.005
Barium 0.7 <0.01 <0.01 0.01 0.08 0.03
Cadmium 0.004 < 0.0005 < 0.0005 < 0.0005 < 0.0005 < 0.0005
Calcuim N/A 2.7 3.5 3.3 4.6 3.1
Conductivity N/A 68 79 88 119 87
Copper 2 0.002 0.001 0.005 0.004 0.005
Iron N/A <0.02 <0.02 0.03 <0.02 0.03
Lead 0.01 < 0.0005 < 0.0005 0.0005 0.0009 0.0007
Magnesium N/A 0.9 1.9 2.2 1.9 1.5
Manganese 0.4 < 0.0005 < 0.0005 < 0.0005 0.0006 0.0005
Mercury 0.007 < 0.0005 < 0.0005 < 0.0005 < 0.0005 < 0.0005
Nickle 0.08 < 0.0005 < 0.0005 < 0.0005 < 0.0005 < 0.0005
Sodium N/A 9 8 11 14 10
Tin N/A <0.0005 <0.0005 <0.0005 <0.0005 <0.0005

Chemical Drinking water standard limits (if assigned) Ngongotahā source Rotoiti source Rotoma Source Rotorua central sources Rotorua East & Okareka source
pH N/Z 6.3 6.4 7.0 6.7 6.8
Nitrate-N 11.3 1.68 0.65 0.01 0.60 0.67
Phosphorus N/A 0.06 0.07 0.01 0.09 0.07
Arsenic 0.01 <0.005 <0.005 <0.005 <0.005 <0.005
Barium 0.7 0.04 <0.01 0.01 <0.01 <0.01
Cadmium 0.004 < 0.0005 < 0.0005 < 0.0005 < 0.0005 < 0.0005
Calcuim N/A 4.0 3.7 2.5 2.3 2.1
Conductivity N/A 91 109 153 85 115
Copper 2 < 0.001 0.003 0.003 0.001 0.004
Iron N/A <0.02 0.04 0.02 <0.02 <0.02
Lead 0.01 < 0.0005 < 0.0005 0.0017 < 0.0005 < 0.0005
Magnesium N/A 2.3 4.9 1.7 1.6 2.2
Manganese 0.4 < 0.0005 0.0006 0.0056 0.0008 0.0009
Mercury 0.007 < 0.0005 < 0.0005 < 0.0005 < 0.0005 < 0.0005
Nickle 0.08 < 0.0005 < 0.0005 < 0.0005 0.0005 < 0.0005
Sodium N/A 10 10 24 10 18
Tin N/A <0.0005 <0.0005 <0.0005 <0.0005 <0.0005
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