Since the acceptance of and commitment to the Millennium Development Goals (MDGs) there have been major gains in reducing the percentage of the global population without access to improved sources of safe water to meet individual basic needs. However in many regions, as more people gain access, the average difficulty of providing access to the remaining population without access increases as the simple or easier solutions are completed and areas of greater water stress remain. In the Pacific island nation of Samoa access stands at approximately 90%. The remaining 10% of the population resides in areas of limited surface or ground water resources. Many of these communities have turned to rainwater harvesting as a supply source. The village of Falelima, Samoa on the island of Savai’i is one such example. Residents meet their fresh water needs through rainwater harvesting but the ability to collect and store rainfall varies greatly between individual families. This report has two goals. First it examines the systems requirements for rainfall collection and storage needed to provide a family with various service levels of water throughout the year by using a model based on the daily annual rainfall data available. The model is used to produce reliability design curves for the village that can allow users or outside agencies to determine how the addition of system capacity will increase the water available to a family. Second, the effects of a grant by the Global Environmental Facility (GEF) for the construction of ferrocement rainwater storage tanks are examined and recommendations are made for further work to ensure all families with a minimum level of service.