utilities in small cities and towns with high rates of poverty and poor network condition. Impact of private sector participation Studies on the impact of private sector participation in Colombia show that it had a positive impact on service quality. There were also significant increases in access in a short time frame under private contracts. However, there are no conclusive results showing that access increased more rapidly under private contracts than in the case of public utilities. There has been a slight average reduction in water losses in privatized utilities. In at least one city (Cartagena), real tariffs declined substantially, indicating that the operator passed on efficiency gains to consumers. None of the studies showed negative impacts of water privatization on access, service quality, operational efficiency or tariff levels. Impact on access According to a study by the World Bank relying on data of Colombia's regulatory agency, private water projects in Colombia have performed well in expanding access. The study notes that progress achieved in Colombia for access to water supply and sewerage services is not due to water privatization per se, but must be credited to good performers in both the public and private sectors, and a national policy that fosters accountability and efficiency. Successful public utilities include EAAB in Bogotá, which made strong progress in access over the last decade, reaching universal coverage. The performance of the public utility EPM in Medellín was comparable for expanding access to that of the largest PPP, that of Barranquilla. Colombia's nine largest and/or oldest PPPs, the two mixed-ownership companies in Barranquilla (serving 1.3 million people) and Cartagena (serving 1 million) also have good records in expanding access. That in Barranquilla made notable progress in both water supply and sewerage services: coverage rose from 86 percent to 96 percent for water and from 70 percent to 93 percent for sewerage (1997–2006). In Cartagena water supply coverage jumped from 74 percent to almost universal coverage, while sewer coverage went up from 62 percent to 79 percent (1996–2006). Cartagena achieved full water supply coverage despite a 50 percent jump in the size of its population during the same period, largely due to the arrival of poor rural migrants. Half a million people gained access and 60 percent of the new connections benefited families in the poorest income quintile. To achieve universal coverage, the operator in Cartagena made extensive use of community bulk-supply schemes that