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.

Council has been working with an independent water engineer to improve processes at the plant.

We have worked through a number of their options for improvement, but they have not been sufficient to lift the boil water notice. On December 9 Council began an Organic Carbon Filtration trial at the plant and we hope this will be a successful solution to lift the boil water notice. This trial will need to run for three months before we are confident of long-term success. If this does not work we will work with the Rural Water Scheme Committee on further options.

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

An advisory is in place after a drinking water sample has returned results with an aluminium level exceeding the drinking water standard of 1mg/L.

The most recent exceedance had a reading of 6.26 mg/L on 07 Jan 2025 at Moa Flat Edievale Rd.

This advisory will remain in place for at least 4 weeks from this date. We require one month of sample results below the drinking water standard before we will lift the aluminium advisory and it usually takes 10-14 working days for samples to be tested and results provided.

The advice received is that no health effects would be expected at these levels of aluminium exposure, even if water was consumed over extended periods of time. This includes effects for people with kidney disease, infants, and children.

You can read more about the water advisory by visiting Council's frequently asked questions page.

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