Traditionally, International FinanceCorporation (IFC) engagement in the water sector has focusedon large municipal infrastructure projects, where individualtransactions are of sufficient scale to attract commercialproject finance. Such projects, involving capital-intensivenetwork infrastructure, can often be commercially attractivebut have generally failed to provide access to poorerconsumers living outside of formal urban centers. So whatabout the 'base of the pyramid' populations thatthose large utility systems fail to reach, ruralcommunities, and sometimes poorer urban customers livingwithin informal settlements and rapidly growing peri-urbanareas? New business models are needed, adapted to thereality of water-supply necessities in the developing world,but with the economies of scale required to achievefinancial sustainability. This smart lesson describes someearly ventures by IFC to invest in and develop marketopportunities in the challenging but potentiallyfar-reaching area of distributed off-grid water supplies.