Water, water everywhere

Undersea freshwater sources could help to counter the impacts of climate change.

- VERONIKA MEDUNA

In the middle of the Wellington suburb of Petone, people line up every day to fill their water bottles from Te Puna Wai Ora, the Spring of Life. The fountain is one of several artesian wells along the Hutt River valley that taps the Waiwhetū aquifer, a vast freshwater lens that stretches underground and continues to run under much of Wellington Harbour.

Matiu/Somes Island, in the middle of the harbour, draws its entire drinking water supply from an offshore groundwater bore, and during dry years, when Wellington's water reservoirs can run low, the capital city relies on this submarine aquifer.

A new detailed study of the harbour floor, pockmarked with freshwater seeps, has delivered a case study that could help scientists find untapped drinking water in other parts of New Zealand and around the world.

Joshu Mountjoy, a marine geoscientist at the National Institute of Water and Atmospheric Research (Niwa), says the study used several techniques - including acoustic surveys and chemical analyses - to map the natural springs where freshwater emerges from the deep. It closes a gap in knowledge about large coastal aquifers around New Zealand.