Tuvalu is an atoll country consisting of nine atolls, with a total land area of 26 km² dispersed over 1.2 million km² of the Pacific Ocean. It has a total population of 11,000, with 4,500 located on the capital atoll of Funafuti. Population pressures on Funafuti are high with a population density of 1600 persons per km².

Approximately 60% of the total annual rainfall occurs during the period November to April. The more northerly islands have the larger variations. Abnormal monthly rainfall is defined as a departure of at least 50% from the average monthly amount. Most years usually have some months of abnormal rainfall but periods lasting more than two months are not common. Air Temperatures are uniformly high all the year round. There is a lack of pronounced seasonal variation and a limited daily variation of 5-6ºC. The mean maximum and minimum temperatures are 31ºC and 25ºC respectively and departure from these means in any month is less than 0.5ºC. (SOPAC 2007a)

Due to the lack of freshwater and the vulnerability of the groundwater reserves water harvesting is needed in Tuvalu. There were a few existing water harvesting measures before the implementation of the EcoSan Project: