 In the 1990s, most utilities improved their economic efficiency and became self-financing companies which were partially handed over to the private sector.Before 1977, urban water and sewer services in Chile were provided by a multitude of public entities.The largest entity was the Sanitation Department (Dirección de Obras Sanitarias, DOS) of the Ministry of Public Works, which was in charge of service provision in towns outside of the two largest cities, Santiago and Valparaíso.