There has been a lot of speculation on the problems of water supply in the fresh water on Rapa Nui in remote past. “The Island has no rivers, creeks or valleys which wash its countryside nor water sources which refresh the thirsty,” wrote Father Sebastian Englert in his book “The Land of Hotu Matua.” And it is true that, previously, fresh water was a limited commodity. But then there were no animals which needed to drink nor clothing, pots or other domestic articles to wash.
Ancient Sources of Fresh Water
The Islanders got their supply from the volcanic craters of Rano Kau, Rano Raraku and Rano Aroi, which have, over the years, served as reservoirs for rain water. In a wet winter, from Rano Aroi, water will rush down several Ava or gullies toward the northeast and the southwest.
This lack of rivers has not been a problem for a regular supply. Several kilometers of subterranean caves, not always with easy access, hold an abundance of fresh water. Rain water filters rapidly through the porous soil and keeps the water table replenished. Water from the craters filters down until it bubbles up among the rocks near to the shore, places well known by the Islanders.
In the past, the natives built Taheta, rock depressions which served to hold water, and Manavai, rock gardens which maintained the humidity in the soil and protected the plants from the wind. The only difficulty was in carrying water to distant places since there were no domestic receptacles except for gourds.
Today’s Drinking Water System
Today the Chilean administration has set up two systems for drinking water on the Island, one within the urban limits of Hanga Roa which covers the full population of the town and another in the rural area around Vaitea. The town of Hanga Roa is supplied from two sources, the gully of Mataveri (Servicio Rano Kau) in the south and the area of Arapiki in the north. The boundary between the two is Te Pito te Henua Street.
The water is pumped from subterranean layers found at more than 60 meters of depth and accumulated together with rain water. There are four bore wells in use (N° 21, 25, 27 and 28) and one in reserve (N° 7). The water extracted from the wells is put through a chemical process in which chlorine is added in minimal quantities (0.3 ppm to 0.5 ppm) to turn it into drinking water, as is required by the Superintendent of Sanitary Services (SISS).
Water Quality and Supply
Mario Zúñiga, head of the Sanitary Division of the public services firm, SASIPA, tells us that: “The water contains many minerals and chemical substances which must be measured once a year. According to the latest results from 2010, all meet the requirements.”
The prime water source on the Island is the rain, with a natural cleaning and filtering process through the rocky and sandy terrain, so it requires less chlorine than water on the continent. To date, Rapa Nui has not had any cases of diseases or poisoning from the public water.
To regulate the flow of the water, there are five large holding tanks located on high points: two on Rano Kau, two on Arapiki and one at Puna Pau. From there the water flows through a network of subterranean pipes to the houses. Today the consumption is 4,000 m³ (141,300 cu. ft.) of water per day, or 70 liters (18.5 gallons) per second. The demand varies with the number of tourists, which in high season can almost double that of residents.
Future Water Supply Projects
“In summer, the pumps are working 24 hours a day and, up til now, we haven’t needed to use the reserve wells,” states Zúñiga, and adds: “Within the contingency plans of SASIPA is a hydrogeologic study to determine the quantity and the quality of the water on the Island. In the case that we find that the sources of fresh water are insufficient, we will have to implement a desalination plant for sea water.”
Other approved projects include the construction of a water system on Maunga Orito (140m – 460 ft. above sea level) as a back-up for the water supply in Hanga Roa, the replacement of pipes and mains with those of greater diameter to improve the volume and the pressure, the application of more modern technology and automation in the processes and, finally, the repair of the water works where chlorination takes place. The urgently-needed study for the installation of a sewage system and water treatment plant, to avoid possible contamination of the subterranean water table from the septic systems and outhouses found in most of the Island homes, remains a mid-term project.
Frequently Asked Questions About Fresh Water on Rapa Nui
Where did ancient Rapanui get their water?
From the volcanic craters of Rano Kau, Rano Raraku, and Rano Aroi, which functioned as rainwater reservoirs, along with underground caves and natural seepage near the coast.
What are Taheta and Manavai?
Taheta were stone depressions used to hold water. Manavai were stone rock gardens that maintained soil moisture and protected plants from the wind, both part of the traditional Rapanui water management system.
How is Rapa Nui supplied with drinking water today?
Through two systems managed by SASIPA: an urban one in Hanga Roa (supplied by the Mataveri and Arapiki sources) and a rural one in Vaitea, drawing from underground wells and treated with chlorine per SISS regulations.
How much water does Rapa Nui consume daily?
Approximately 4,000 m³ of water per day (70 liters per second), a demand that varies significantly with tourist influx, which can nearly double the resident population during high season.
2 Responses
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Thank you for the fascinating info on the water supply and management. Also it is a revelation to me that Easter Island is owned by Chile when it is in Polynesia…late to the party i guess. Love learning about the mysteries of the past. Bibi