Improvements to Marton’s water supply progress as testing continues on new system

Rangitīkei District Council drilled a new bore at Tūtaenui Reservoir in July to improve Marton's water quality.

The trial water treatment plant in Marton is showing encouraging signs as the local council works to improve the town’s water quality.

A bore was drilled at the Tūtaenui Reservoir site in 2024 and testing trials have progressed since July this year.

A bore is a narrow, drilled hole or well that provides access to groundwater.

The Rangitīkei town has had water quality issues for years because of high levels of manganese (a common mineral) and geosmin (produced by algae) in its surrounding water.

Residents have experienced discoloured, smelly and unpleasant-tasting drinking water.

The Marton Water Supply Strategy, as part of the 2021-2031 Long Term Plan, aimed to change the water supply source from dam surface water to bore groundwater to remove geosmin.

Rangitīkei District Council’s assets, infrastructure and projects group manager Arno Benadie said the pilot plant was using a nanofiltration system to tackle mineral content.

“Our bore water will have a higher mineral content of iron, manganese, ammonia and calcium hardness,” he said.

“So far in the testing that has been done, initial results are looking promising that these are able to be removed by the nanofiltration system.”

The system is coupled with a biological sand filter pre-treatment process.

A second bore was drilled in July this year which, in addition to the first bore, will eventually create the new water treatment plant.

The in-depth testing for the new bore has been completed but the data is not yet available, with results expected within the next month.

In a November 10 Facebook post, the council asked Marton residents to conserve water because the 100-year-old water treatment plant was “really struggling”.

“We’re stoked to see summer make an appearance in Rangitīkei but recent weather is making it hard to keep everything running smoothly,” the post said.

Benadie said teams were trying to “challenge” the new test plant by trialling it under a wider range of conditions, such as higher flow rates.

“This is so that the eventual full-scale plant will be based on a sound set of data. We expect this phase to continue until we are sure that we get the best-quality data to use in the final plant design,” Benadie said.

“Testing on this scale can produce unexpected results and, while the results have been encouraging so far, it’s crucial we take the time to ensure we have captured all the information needed to progress to the next stages with confidence.”

The council is discussing options for what will happen to the dams once the new water supply is in place.

Potential options include reducing water levels to below risk level or full decommissioning of the dams.

Benadie said the water treatment plant project was progressing as a matter of urgency and he sympathised with residents who were affected.

“We know it’s been a long journey with some delays; however, the Marton water strategy team is working at pace to complete this important project and future-proof Marton’s drinking water for generations.”

Fin Ocheduszko Brown is a multimedia journalist based in Whanganui.