Moa Flat & Heriot - Boil water & aluminium reminder

Consumers in Heriot and on the Moa Flat Rural Water Scheme are reminded that a boil water notice is in place.

Separately, an aluminium advisory is also in place for the Moa Flat Rural Water Scheme.

About the boil water notice

New drinking water standards were introduced in November 2022. Unfortunately processes at the Moa Flat Water Treatment Plant, which was designed prior to this, do not treat the water to meet these standards for protozoal and bacterial measures.

The water source is from Timber Creek, approximately 17km upstream of the plant. The water goes into a large pond which has about two months storage capacity. The colour, natural organics and low levels of silt in this water make it difficult to treat. It needs to comply consistently with requirements of the Drinking Water Quality Assurance Rules.

The Council has been working with an independent water engineer to improve processes at the Moa Flat and North Bruce water treatment plants. Council have initiated the second phase of an Organic Carbon Filtration trial at the Moa Flat plant, following the conclusion of the first trial in March 2025. The initial trial focused on passing raw water through a pilot filter column, while the current phase entails treating water with a coagulant to encourage the formation of floc, which will then be removed through settling or within the filter media. This trial has been ongoing for two weeks, and if it proves successful could lead to a long-term solution allowing for the lifting of the boil water notice at the plant.

While we are making progress on coming up with a solution it will take some time to lift the boil water notice. As you will appreciate once we agree on the solution, we would need to get pricing from contractors and their availability to undertake required upgrades. Following completion of the work we would need to be confident that the solution is effective, then reticulation sampling and flushing of the network begins. As this is a large rural scheme, we would also need to ensure all non-compliant water throughout the scheme including water stored in reservoirs and tanks is gone. Following that we are required to have 7 days of clear sampling before we can lift the boil water notice.

You can read more about this update here.

Council advises anyone using water from their tap for consumption (including teeth cleaning and food preparation such as washing fruit and vegetables) should boil it for 1 minute before it is used.

You can bring your own clean containers to fill at the water tank available at the Heriot School grounds.

You can read our boil water FAQs at www.cluthadc.govt.nz/boil-water-faqs

About the advisory

The aluminium advisory remains in place as test results continue to show some elevated aluminium levels from time to time.

Read more about the aluminium advisory including advice and the latest test results at www.cluthadc.govt.nz/advisory

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