In this article, we document as many ethnohistoric accounts of fresh water usage on Rapa Nui as we were able to locate. This review probably misses some sources but we tried to be as comprehensive as possible. This article ideally addresses concerns of some critics who asserted that coastal seeps simply were not important or that the main source of fresh water was the crater lakes. Based on all the available documentation that exists, it appears as if these critics have never spent time on the island’s landscape seeking sources of drinking water and/or haven’t carefully reviewed the literature. We hope that this publication helps set the baseline record straight: while people made use of drinking water wherever they could find it (caves, sugarcane, taheta, lakes), some of the key sources of consistent fresh water for communities were coastal seeps.
http://thepolynesiansociety.org/jps/index.php/JPS/article/view/411 You can also download the full text here: https://orb.binghamton.edu/anthropology_fac/42