Photo: AFP
The Marlborough District Council is considering temporarily treating Havelock's water supply with ultraviolet light after the regulator issued a boil water notice.
Taumata Arowai issued the notice last Wednesday as a precautionary measure due to the risk of parasitic contamination.
A new treatment plant was due to be completed by 2028, however, if a temporary solution was found the notice could be lifted well ahead of that date.
Council assets and services manager Richard Coningham said the risk of contamination in Havelock had not changed, but the drinking water requirements in the Water Services Act 2021 were more stringent.
Water supplies in New Zealand required a multi-barrier approach - a range of processes, procedures and tools to protect and treat water.
"Although chlorine is used in the Havelock supply, it doesn't protect from the risk - however small - of protozoa getting into the supply," Coningham said.
Protozoa are single-celled parasites, like cryptosporidium and giardia, that make can make people sick. They can be removed from water with filters or inactivated using UV light so they do not pose a health risk.
People in Havelock were being told to boil water used for drinking, cooking, brushing teeth and washing food.
Coningham said the council was working through a number of options and planned to have a solution by the end of the week.
The new $14 million water treatment plant planned for Havelock would use a multi-barrier approach, including filtration, chlorine and UV.
"The plant upgrade has been planned for some years and budget is set aside in the council's Long Term Plan. However it has been difficult to secure a new site, with few land options available in the town or nearby," Coningham said.
The council had now found a site and was planning and designing a new treatment plant, for completion in early 2028.
Land purchase negotiations were in the final stages and a new road would be built to provide access.
Construction tendering would follow.
