Release – 15 July 2025

A precautionary boil water advisory has been issued for residents connected to the Patearoa and Ranfurly water supplies, while upgrades are underway for both treatment plants.

The advisory will remain in effect until these upgrades are completed in December 2025.

The Ranfurly and Patearoa water treatment processes use chlorine to remove any risk of bacteria in the water supply, but they do not have a treatment barrier for protozoa.

Protozoa are microscopic organisms, such as Cryptosporidium and Giardia, which can enter the water from animal faeces. If present, protozoa can cause gastrointestinal illness such as vomiting and diarrhoea. Babies, young children, pregnant women, the elderly and people who have weakened immune systems are more at risk of illness. 

Water Treatment Plant Upgrades

Council approved the procurement of water treatment plant upgrades in January 2025, awarding the contract to Fulton Hogan to upgrade both the Ranfurly and Patearoa treatment plants. The new treatment equipment is being pre-fabricated off-site and will be relocated when ready for installation. The upgrades are expected to be completed by December 2025.

The treatment plant upgrades include the addition of filtration and ultraviolet treatment systems. These will supplement existing treatment processes to deliver safe drinking water that meets New Zealand Drinking Water Standards. The UV treatment will eliminate protozoa risks and the filtration system will improve the resilience of these supplies and enable them to continue operating in a wider range of weather conditions.

“There has been no change to the water supply on these schemes. However, the continued absence of protozoa barriers presents a risk to public health,” CODC Group Manager – Three Waters, Julie Muir said.

“We understand this advisory will be an inconvenience for residents, and Council is committed to providing monthly progress updates to the community on the upgrades. Taking this step will help protect the health of our communities until the new treatment systems are in place. Boiling water is an effective way to remove the risk of illness caused by protozoa.”

Health Information

The source water for the Patearoa and Ranfurly schemes comes from the Sowburn and Eweburn rivers. These are surface water sources that may be accessed by animals. If animal faeces enter the water, protozoa may be introduced into the supply, posing a potential health risk.

Residents connected to the Patearoa and Ranfurly water supplies must boil all water used for:

• Drinking water
• Brushing teeth
• Preparing food
• Washing fruits and vegetables
• Making ice, baby formula, juice and cold beverages

How to boil water for drinking:

Bring water to a rolling boil (where bubbles appear and do not disappear when the water is stirred) for one minute or boil a full electric jug until it switches off.

Cool the water (do not use ice cubes to do this) and pour it into a clean container with a lid.

Refrigerate until needed.

Residents with well-maintained, high-quality cartridge filters followed by ultraviolet disinfection units that supply their entire house do not need to boil their water.

Residents are encouraged to share this information with tenants, household members and others who may not have received this advisory directly.

Further information is available on:

The CODC website

Taumata Arowai website

Council appreciates the community's cooperation and understanding while this upgrade work is completed.

Read more: Urgent work on drinking water plants and upgrades