The document describes a rainwater harvesting system developed for smallholder farmers in Nicaragua to ensure a sustainable water supply. The system collects and stores rainwater in an underground reservoir for irrigation and domestic use during the 4-month dry season. It was implemented on 42 farms in 2015 and another 42 farms in 2016. The system costs $203 USD per farm to install and provides over 64 cubic meters of water storage to meet farms' 16 cubic meter per month needs during the dry season, ensuring water security when rainfall is low.