Sources:
UNSD/UNEP Questionnaires on Environment Statistics, Water section.
Eurostat environment statistics main tables and data base. http://epp.eurostat.ec.europa.eu/portal/page/portal/environment/introduction).
OECD Environmental Data Compendium, Inland Waters section.
Footnotes:
- Refers to reticulated sewerage.
- Data refer to urban population only.
- OECD secretariat estimates based on MUD Municipal Waste Water Database.
- Information provided by the sanitary industry that operates in urban sectors to the Supervision of Sanitation Service with respect to the percentage of residential buildings connected to the sewage system.
- Information provided by the sanitary industry that operates in urban sectors to the Supervision of Sanitation Services with respect to the percentage of connected residential buildings to the sewage system whose collected water receives treatment.
- It corresponds to the city of Santo Domingo and represents 350,063 inhabitants.
- The values relate only to the population of Conakry. There are no statistics for the cities of the interior of the country. However, in all cities almost all of the people are served by either septic tanks or latrines. In rural areas, latrines exist in all large villages (more than 500 inhabitants). In the city of Conakry, despite the weakness of the single system of purification, the entire population is served by septic tanks or by family latrines.
- Population connected may include population not connected by pipe.
- No urban wastewater treatment plant.
- Percentages based on population living in individual housing.
- Estimates based on treated waste water.
- Data available for this section relate primarily to the connections, the discharge of wastewater into the ocean, to treatment plants and the length of the sewerage network. Regarding the connections, the vast majority of the population lacks access to the network. Among the population of cities that have a sewerage system, only 23% are connected.
- Estimated value.
- Data refer to population served by the National Water and Sewerage Corporation (NWSC). The NWSC only provides service in larger towns and cities.
- Data refer to England and Wales and to the financial year (April to March).
- This is the proportion of inhabitants connected to the national wastewater collection system (the sanitation and sewerage system) in urban areas only, not in the country as a whole.
Definitions & Technical notes:
Wastewater refers to water which is of no further value to the purpose for which it was used because of its quality, quantity or time of occurrence. However, wastewater from one user can be a potential supply to a user elsewhere.
Wastewater collecting system means a system of conduits which collect and conduct wastewater. Collecting systems are often operated by public authorities or semi-public associations.
Population connected to wastewater collecting system is the percentage of population connected to the wastewater collecting systems (sewerage). Wastewater collecting systems may deliver wastewater to treatment plants or may discharge it without treatment to the environment.
Wastewater treatment is all treatment of wastewater in wastewater treatment plants. Wastewater treatment plants are usually operated by public authorities or by private companies working by order of public authorities. Includes wastewater delivered to treatment plants by trucks.
Population connected to wastewater treatment is the percentage of population whose wastewater is treated at wastewater treatment plants.
Data Quality:
Data on population connected to wastewater collecting system and wastewater treatment can be obtained from municipalities or through household surveys. Household surveys usually give more accurate results, since they do not rely on sometimes incomplete information about or held by municipalities. In general, data quality can be considered to be fairly good.
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