After a decade of discussions, action will finally be taken on an at-risk water supply in Northern Hawke's Bay.

The electoral roll has recently opened for a Wairoa District Council binding referendum, which will determine whether or not a small coastal settlement's untreated water supply is to be closed.

Mahanga is a beachside town near Mahia which has about 60 properties, around half of which are occupied by permanent residents.

Although the water supply there is supplementary, since 2007 the council has discussed its upgrade due to the potential health risks it poses.


The supply - which originates from a shallow bore - has been designated as non-potable, and there is a permanent boil water notice advertised to users of the supply. Residents are also required to have their own tanks for collection of rainwater.

The supply regularly returns contaminated samples, and does not meet the New Zealand Drinking Water Standards (NZDWS) because there is "no effective barrier to waterborne disease entering the drinking water supply".

The supply also lacks enough pressure to be suitable for firefighting - even though there are hydrants in the reticulation.

Although an upgrade has been discussed for a decade, the risks posed by the supply were highlighted following the Havelock North water contamination crisis in August last year.

So, in September residents will cast their vote as to whether or not the supply should be closed.

The binding referendum means that if 75 per cent or more of the votes cast are in favour of the closure, the supply will be closed. If more than 25 per cent of the votes are against the closure, it will remain open.

Last year it was expected that capital costs per connection for upgrade would be less than $5000 per property, and operational costs would be similar to Wairoa water charges.

Wairoa's Long Term Plan 2015-2025 notes a sum of $200,000 was allocated for a treatment upgrade to the Mahanga supply before 2020.

-The Electoral Roll to be used for the referendum closes at 4pm on Thursday, August 3. It can be inspected during normal business hours at the Wairoa District Council Offices.
-The referendum will be held Friday, September 29.