Sources:
UNSD/UNEP Questionnaires on Environment Statistics, Water section
OECD/Eurostat Questionnaire on the State of the Environment, Water section
OECD Environmental Data Compendium, Inland Waters section
Footnotes:
- Data obtained from household surveys (NSS).
- Refers to reticulated sewerage.
- For Baku, the population connected was 80%, whereas the estimate was 15-20% in other cities.
- 2005 data.
- Data refer to urban population only.
- Data source: household survey; data refer to households provided with drainage system.
- OECD secretariat estimates based on MUD Municipal Waste Water Database.
- It corresponds to the city of Santo Domingo and represents 350,063 inhabitants.
- 2004 data.
- The values given in this table 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.
- Data for Jakarta City only.
- 1999 data.
- 1997 data.
- 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.
- 2000 data.
- 2007 data.
- 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.
- Data refer to England and Wales and to the financial year (April to March).
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. Cooling water is included.
Urban wastewater collection system means a system of conduits which collect and conduct urban wastewater. Collecting systems are often operated by public authorities or semi-public associations.
Population connected to urban wastewater collection
system is the percentage of the resident 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.
Urban wastewater treatment is all treatment of wastewater in urban wastewater treatment plants (UWWTP’s). UWWTP’s 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 urban wastewater treatment is the percentage of the resident 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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