Sand dams capture and store water for use during the dry season in rural communities. A year long field study of three sand dams in Tanzania showed that sand dams are not a suitable habitat for aquatic insects. They capture plenty of water, but most is evaporated during the first few months of the dry season. Sand dams positively impact vegetation and minimally impact erosion. Community water security can be increased by sand dams, but site characteristics and construction are important factors.