Our work grows out of very recent cutting-edge research revealing severe water insecurity in high income economies. In the US, for example, more than 2 million people live without household access to clean water (US Water Alliance 2019). Much of this household water insecurity occurs in small rural and often marginalized communities including colonias (Dietz and Meehan 2019). Colonias are small, unincorporated settlements in the US Southwest, on the US-Mexico border from Texas to California that typically lack standard regulated water infrastructure, but instead deliver water service through informal water systems. The lack of complete access to water services for some in the US is often considered surprising given the sophistication of drinking and waste water system infrastructure in large US cities (Wescoat 2007). New small-scale solutions are required to reach 100% coverage for water security in the US. In this project, we take a justice-oriented, pro-poor, community-based participatory approach to address water insecurity in colonias in AZ, CA, NM, TX using innovations in water sharing, social infrastructure, and physical infrastructure.