While many New Zealand towns get their water from rivers, Christchurch is unique because its water supply is drawn from the artesian basin under the city.
Christchurch water is naturally filtered through the gravel beds and sand laid down by glaciers and rivers during the formation of the Canterbury Plains. This means that the water doesn’t need to be chemically treated or filtered to remove bacteria or other matter, because it comes from the ground clear, refreshing and ready-to-drink, meeting the New Zealand drinking water standards without human intervention.
Over time the underground artesian basin is recharged predominantly from the Waimakariri River, and also from rainfall that has seeped from the surface down into pores in the sand and shingle.
The water-filled bands of gravel are called aquifers, underground streams designed by nature and replenished in the recharge zone. Sometimes the water flows naturally to above ground from the wells drilled into these gravel beds. These are called artesian wells.