Holding the equivalent of half the volume of ground water found across the region, a newly discovered freshwater aquifer could provide a new water source for Canterbury.
The aquifer which lies just 20 metres below sea level off the coast of the South Island, between Timaru and Ashburton holds as much as 2,000 cubic kilometres of fresh water.
NIWA scientist Joshu Mountjoy says indications of fresh water were discovered when a drilling project in 2012 found traces of brackish water, a mixture of salt and freshwater.
This led to a further investigation by NIWA in 2017 collecting electromagnetic data to determine how much freshwater was held below the seabed.
The aquifer is being partly replenished through a flow of groundwater from the coastline between Timaru and Ashburton.
However, Mr Mountjoy says most of the fresh water was trapped during the last three Ice Ages when the sea level was over 100 metres lower than it is today.
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