This paper describes the importance of small-scale private sector or NGO providers of water and sanitation in a great range of urban areas in Africa, Asia and Latin America. It includes many examples of where - contrary to conventional wisdom - they provide good quality, low-cost services. Without these operations, large sections of the South’s urban populations, including tens of millions of low-income households, would be worse off. Yet these generally operate with no subsidy and have to recover their costs. This paper discusses how public policy can support (or at least not seriously constrain) small-scale entrepreneurs in water and sanitation provision while ensuring checks on the quality and price of the services they provide.