Background to Martinborough’s water chlorination

In 2011 a UV disinfection Plant was installed to provide protozoa compliance. A chlorine dosing plant was added in 2011/12 to allow for emergency chlorination and potential movement to a chlorinated supply.
The Havelock North Drinking Water Inquiry (re: August 2016 outbreak of gastroenteritis) changed the operating landscape for the supply of safe drinking water across New Zealand.
Following a positive E.coli test result from routine sampling of Martinborough’s water supply network, SWDC issued a boil water notice on 1 February 2019. A malfunction in the UV disinfection plant following a power cut resulted in untreated water being pumped into the reticulation network for 15 hours. A flushing programmed followed and the boil water notice was lifted on 21 February 2019.
A decision was made not to chlorinate at that time due to the likely problem of significant water quality issues and complaints due to discoloured water. Discolouration would have been from the high manganese content of the water and biofilm within the supply network.
On 9 April 2019, a further boil water notice was issued following a positive E.coli test result for samples taken near the Martinborough reservoir and a location on Shooting Butts Road. A number of potential sources were investigated, including backflow prevention mechanisms to private properties, but the source of the contamination could not be confirmed.
Temporary chlorination was expected by Regional Public Health in order for the boil water notice to be lifted. This happened after winemakers were given two weeks to make alternate arrangements for their water supply.
The chlorination system was upgraded to allow it to operate automatically and deliver a set dose based on flow rate. Water quality has not been an issue to date because Bore 4 has a suitably low manganese level to supply Martinborough without significant risk of water discolouration.
However the current situation is temporary. We are committed to pursuing a sustainable permanent chlorination system. Given the tight timeframes, effectively removing the manganese from the existing town water supply (and being able to use more than one bore) is the best course of action.

Back to Martinborough water project page.