All data displayed in the Water Information System for Europe (WISE) are reported by Member States or other countries reporting to the European Commission (EC) or the European Environment Agency (EEA). The data are reported in the context of the official reporting on the basis of EU legislation, in particular the Water Framework Directive (2000/60/EC), the Urban Waste Water Directive (91/271/EEC) or the Bathing Water Directive (76/160/EEC, 2006/7/EC) or the data are submitted on a voluntary basis in the context of the EIONET agreements of the EEA.

The data are displayed in the way they were reported and only for some of the data, quality control and quality assurance has taken place. In particular for data that were only recently submitted, errors or misrepresentations may occur. It is the intention of the EEA and the cooperating services of the EC to ask the Member State to correct data whenever an error is identified and to update the data accordingly. Furthermore, a systematic and comprehensive quality control and quality assurance is developing process and will be put in place in order to ensure the highest possible quality and accuracy of the data.

Until then, the data are not officially published and are not necessarily authorised by the European Commission or other Commission Services or the European Environment Agency. Official published data and maps related to EU water legislation can be found at the web pages of EC-DG Environment: http://ec.europa.eu/environment/water/index.html.

The data also do not necessarily represent the official position of the Member States concerned. Official data and more information on implementation of water policy can be found at the web pages of the responsible institutions in the Member States. An indicative list of some relevant web pages can be found at: http://ec.europa.eu/atoz_en.htm.

To derive the volume per capita, data on water abstraction are divided by population per country or RBD. The RBD population dataset is not a product of reporting, but estimated calculations based on population density proxies (population data from NUTSIII level have been disaggregated per km² and aggregated back at RBD scale based on the RBD area). 

The following sources of data on freshwater abstraction have been used:

• Data extracted from the Waterbase - Water Quantity collected from the MSs through the WISE-SoE process between 2009 and 2011. The URL to the dataset is: http://www.eea.europa.eu/data-and-maps/data/waterbase-water-quantity-6
• Data extracted from the OECD/ESTAT Joint Questionnaire on Inland Waters (most recent year) collected from national statistical agencies through Eurostat. The period that the data was extracted ranges from 2001 to 2009. 2001 data is an exception for Turkey that does not have any later year data availability with the rest of the Eurostat data ranging from 2005 to 2009. Water Abstraction Eurostat data was available at country and RBD level at http://epp.eurostat.ec.europa.eu/portal/page/portal/statistics/search_database
• Data extracted from the WISE electronic summary reported under the WFD for the years 2004 to 2008 with the exception of Italy that has not reported the year of the provided water abstraction data.
• Data has been retrieved by the MS reply to the DG ENV "Questionnaire on the scope of WSD" distributed for the purposes of the 2007 EU Communication on WSD. This data was only used in the case of Portugal.
• Population: RBD level: This information is not a product of reporting, but estimated calculations based on population density proxies (population data from NUTSIII level have been disaggregated per km2 and aggregated back at RBD scale based on the RBD area). Data was extracted from http://appsso.eurostat.ec.europa.eu/nui/show.do?dataset=demo_r_d2jan&lang=en
  Population: Country level: This data was taken directly from Eurostat’s website for the latest year available (2011) from http://appsso.eurostat.ec.europa.eu/nui/show.do?dataset=demo_pjan&lang=en
• The River Basin District layer was derived from the WFD River Basin Districts f1v4 shapefile (published 1st July 2011).
• The Country layer was derived by the CNTR_RG_100K_2004_ETRS_LAEA_Europe_clip_v2” shapefile (published 12/07/2011).