This layer represents the percentage of the population who is connected to a wastewater treatment plan for 36 countries (29 in Europe and North America, 3 in Asia and the Pacific, 3 in Latin America and the Caribbean, and 1 in Africa). However, data are available from 1975 to 2014 for 37 countries. This indicator presents sewage treatment connection rates, i.e. the percentage of the population connected to a wastewater treatment plant. “Connected” means actually connected to a wastewater treatment plant through a public sewage network. It does not take into account independent private facilities, used where public systems are not economic.For more information, visit the OECD database: https://data.oecd.org/water/waste-water-treatment.htm