Easter Island (Rapa Nui to locals) is isolated in the eastern Pacific Ocean about 4 and 5 hours flying time east of and west of Papeete and Santiago. The island is a triangle shaped land mass of 166 square kilometres with three major extinct volanic forms at each apex - the highest peak being 507m above sea level.

Like many small island states Rapa Nui depends on groundwater for safe drinking water.

Various groundwater hydrogeological studies have been undertaken. Average annual rainfall varies from 1100 mm/yr on the  coast to 1500 mm/yr on the higher slopes. After allowances for evapotranspiration rainfall recharge of the groundwater aquifer is estimated to be 270 to 400 mm/yr or a total across the island of 3200 to 4700 litres/sec of which the majority flows to the coast.  The central water supply for the main town of Hanga Roa (33 litres/sec) is drawn from 4 wells near the coast that are only recharged by a small surface area of the island. The water supply which is already under stress is susceptible to climate change affecting rainfall and evapotranspiraion (in combination can result in annual and/or seasonal reductions in available water) as well as sea level rise resulting in salt water intrusion.

Contamination of the groundwater from "black wells" throughout Hanga Roa creates an extreme risk if with climate change this pollution were to reach the supply wells.

Adaptation actions include (i) drilling new wells for supply, monitoring and evaluation (ii) advanced groundwater computer modelling (iii) removal of "black wells" and replacement with septic tank/gravel/infiltration wetland systems.