Council must confirm a funded plan to bring the Montalto water supply up to current drinking water standards.

Taumata Arowai, New Zealand’s drinking water regulator, has asked Council to address the scheme’s non-compliance and develop an action plan.

The regulator considers Montalto to be a mixed-use rural supply. To begin moving toward compliance, the supply needs to have storage, end-point treatment with filtration and UV disinfection.

Council is currently conducting a trial at three households on the scheme to see if end point treatment of the water supplied by the current network is viable and it is showing positive results.

Each of the trial properties has a storage tank, pressure pump, and end point treatment consisting of an off-the-shelf domestic cartridge filtration setup (20 micron, 1 micron, and charcoal) and a domestic UV disinfection unit.

Any solution for the future needs to make drinking water safe and meet the law. It also needs to be affordable and fair about who pays.

The current water supply at Montalto is not compliant with the Water Services Act 2021 and current Drinking Water Quality Assurance Rules (DWQAR), and the following issues have been identified:

• There is no filtration
• The UV reactor is old and is not validated to current standards
• UV transmittance can be as low as 20%
• Chlorine dosing needs to be very high and disinfection is a by-product risk

The raw water can be poor quality, especially after heavy rain and because of this, the supply has been on a permanent boil water notice since 20 February 2018.

The pipe network is another major issue with no backflow prevention in place. The network consists of about 80km of pipes, was installed in the 1960s, and would need replacing if Council continued to rely on it for drinking water.

At the moment, the 34 connected properties pay the full cost of running the Montalto supply, as Montalto users are not part of the wider district water group. The supply is used for both household water and stockwater, but only about 10 percent of the water supplied by the network is used by households. The rest is used mainly for livestock.

Council has looked at a range of options and wants your feedback before deciding.

We want to know which option you support and why.

The costs shown under each option are estimates for comparison purposes only. Final costs may change after design work, approvals and decisions are made.

Options 1, 2 and 3 also have two possible ways to pay for them.

Council has budgeted money in its Annual Plan 2026/27 for work on the Montalto scheme. Under the preferred option, this could help pay for rainwater storage tanks and treatment units at each house. The possible funding models are:

Funding Model A: Only Montalto water users pay for the option (this is the current approach).

Funding Model B: Montalto joins the wider water group, and all group water ratepayers help pay. This model would likely require a discussion with the wider community, and be consulted on as part of the Long Term Plan.

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