Martinborough water treatment plant was built in 2011. Water supplied to Martinborough is extracted from bores at Herricks Wells. The plant has a design capacity of up to 4.3 million litres daily (ML/d), but typically treats around 1.2 ML/d on average.

The plant treats the water using UV disinfection, pH correction and chlorination and supplies directly into the network. Excess water not used in the town is stored in four reservoirs to the east of the town.

Currently, water supply to Martinborough comes from just one of the four available bores. This bore has the lowest levels of manganese, which makes it suitable for chlorination. When chlorine is added to water with high levels of manganese it becomes discoloured, which is why the other bores are not used currently.

South Wairarapa District Council made the decision to permanently chlorinate Martinborough’s water supply in September 2019, in addition to treatment using UV, to provide a multi-barrier approach for safe drinking water. In order to be able to supply Martinborough town with water from all four bores at Herricks Wells, a Manganese reduction plant is required and is in the construction stage.

Supply from Herricks Wells accounts for around 28 percent of South Wairarapa’s total water supply volume in a typical year.