Atlas de la Polynésie française, Paris, ORSTOM, planche 99.
French Polynesia offers the singular spectacle of islands enjoying abundant rainfall where the water supply raises difficulties. Such a state of affairs can largely be attributed to the communes, which since 1977 have been reponsible for the upkeep of systems built by the Public Works Department in the 1950's and early 1960's. the badly maintained piping is getting old and leakage is increasing. On Tahiti, for example, the mains supply is about 55% efficient. The municipal councils are short of money, because water charges are kept very low to humour people's refusal to be charged for such a gift from the heavens. This situation hinders renovation work on the supply system and causes uncontrolled consumption. Three quarters of the water pumped in Tahiti is wasted. Water potability is no longer reliable, because the surface water catchment is all-too-often left untreated.
Papeete town council is, however, now rationalising this sector. A billing arrangement is gradually coming into existence and the shift to drainage galleries rather catchment systems has improved water quality. In the other communes of the Society Islands, the public water supply frequently fails to reach a potable standard ; more than half of this water comes from catchments. Some inhabitants are beginning to receive supply from bores and drainage galleries. The smallest islands, such as Maupiti and Bora Bora, suffer shortage, especially during the dry season. Community land ownership and the administrative structure on Tahaa are hindering the rational organisation of water supply there.
The Austral and Gambier Islands have little in the way of surface water resources and only by good management could a relaible supply be provided. Problems in the Marquesas are more related to quality than to quantity. Only Tahuata and part of Fatu Hiva sometimes experience water shortages.
But it is in the Tuamotu archipelago, made up of a multitude of atolls, where the public water supply problem is felt the most acutely. On these low islands, only groundwater and the catchment and storage of rainwater can be relied upon. People live on ten litres of water per person per day on a permanent basis. Although rainfall is only slight, the collection of rainwater runoff from rooves is a technique that could be perfected. In the central Tuamotu, current facilities operate at about 45% efficiency. Tapping the sweet water lens is no panacea, because the problem of replenishment then arises. At present, only eight islands have a water supply system that draws on the sweet water table. Hao and Moruroa meet their substantial demand with thermo-compression sea water desalination plants.