In Lebanon, the organization of the water legislation dates back to as far as antiquity. While customs and habits used to govern water in the past, codified laws and their associated legal infrastructure are present nowadays, and cohabitate with persisting unofficial law. Mesopotamian, Roman, Ottoman, and French water laws were superimposed on Muslim customs and practices and traditional Arab social water arrangements in Lebanon, throughout a long history of conquests or mandates. Traditional customs and practices of water use that evolved into lore are still prevailing today, and go hand in hand with a palimpsest of water laws. Through a review of the co-evolution of thousands of years of written and unwritten water-related texts, the unique features of a hydro-palimpsest that combines formal and informal systems are put into value in an effort to explore their future potential in the sound and efficient management of water, in light of rapid global changes affecting the resource.