What lies beneath

Groundwater can be defined as freshwater contained in aquifers (water-bearing layers) below ground. The Canterbury Plains have their own, unique system of aquifers. Beneath alluvial fans deposited over millions of years by rivers carrying gravel and sediment from the Southern Alps, there are networks of aquifers arranged like the layers in a club sandwich. These consist of layers of water-filled gravel that are the source of groundwater for farms, businesses, and our homes.  In Canterbury, due to a dramatic increase in demand, groundwater use now surpasses out-of-river water use.

Some of these aquifers contain water which fell as snow on the Southern Alps and rain in the foothills thousands of years ago. Others have been filled by seepage from our major braided rivers and from rain soaking into 8000sq km of the Canterbury plains. Throughout the region, on both the plains and in the hill country, aquifers have different characteristics depending on soil types, the geological formations under the ground and the affects of seismic activity over thousands of years.

Environment Canterbury’s management of groundwater has immense significance for future productivity in the region, for the maintenance of ecosystems sustained by groundwater and for the Christchurch metropolitan water supply.
Christchurch’s drinking water aquifers yield water of exceptional quality and purity. All the water for a thirsty city is supplied untainted and untreated to thousands of Christchurch homes and businesses each day.