1.1. Contact organisation
Statistical Office of the European Commission (Eurostat)
1.2. Contact organisation unit
Unit E2: Environmental statistics and accounts; sustainable development
1.3. Contact name
Confidential because of GDPR
1.4. Contact person function
Confidential because of GDPR
1.5. Contact mail address
e-mail contact : ESTAT-SDG-MONITORING@ec.europa.eu
1.6. Contact email address
Confidential because of GDPR
1.7. Contact phone number
Confidential because of GDPR
1.8. Contact fax number
Confidential because of GDPR
2.1. Metadata last certified
19 December 20242.2. Metadata last posted
14 April 20252.3. Metadata last update
14 April 2025The indicator is part of the EU Sustainable Development Goals (SDG) indicator set. It is used to monitor progress towards SDG 6 on clean water and sanitation, which is embedded in the European Commission’s 2024-2029 priorities under 'Sustaining our quality of life: Food security, water and nature'.
Among other things, SDG 6 calls for ensuring universal access to safe and affordable drinking water, sanitation and hygiene, and ending open defecation. It also aims at improving water quality and water-use efficiency and encouraging sustainable abstractions and supply of freshwater. SDG 15 seeks to protect, restore and promote the conservation and sustainable use of terrestrial, inland water and mountain ecosystems.
This indicator can be considered similar to global SDG indicator 6.3.2 "Proportion of bodies of water with good ambient water quality".
Protection of water resources, water ecosystems and of drinking and bathing water is at the cornerstone of EU environmental policy. EU water policy provides a framework to comprehensively address water protection and for achieving good status for inland surface waters, transitional waters, coastal waters and groundwater. The Water Framework Directive is the main European legislation aiming to prevent water pollution and the EU Biodiversity Strategy for 2030 supports the implementation of the Water Framework Directive’s objective by requiring Member States to restore freshwater ecosystems.
The 8th Environment Action Programme sets the environmental policy agenda for the years from 2021 to 2030 and explicitly mentions water-related issues in two of its six priority objectives. These two objectives are: (1) pursuing a zero-pollution ambition for a toxic free-environment, including for air, water and soil and protecting the health and well-being of citizens from environment-related risks and impacts; and (2) protecting, preserving and restoring biodiversity and enhancing natural capital, notably air, water, soil, and forest, freshwater, wetland and marine ecosystems.
4.1. Data description
Biochemical oxygen demand (BOD) of water bodies is a key indicator to measure water quality. It refers to the amount of oxygen that aerobic microorganisms need to decompose organic substances in a water sample over a five-day period at 20 °C (BOD5). High BOD5 values usually indicate organic pollution, which affects water quality and the aquatic environment. Organic pollution caused by discharges from wastewater treatment plants, industrial effluents and agricultural run-off increase BOD. The cleanest rivers have a five-day BOD of less than 1 milligram per litre (mg/L). Moderately polluted rivers show values ranging from 2 to 8 mg/L.
Data presented for this indicator stem from the European Environment Agency (EEA) Waterbase database on the status and quality of Europe's rivers.
For time series analyses, only complete series after inter/extrapolation are used. As monitoring sites change over time, this leads to a recalculation of the whole time series with each update. Complete time series for 2000 – 2022 are based on a total of 692 monitoring sites (646 within 17 EU Member States) distributed over the following countries (number of monitoring sites in parentheses): Belgium (36), Bulgaria (66), Czechia (21), Estonia (35), Ireland (14), Spain (168), Croatia (16), Italy (49), Cyprus (4), Latvia (16), Lithuania (22), Austria (1), Poland (90), Romania (85), Slovenia (10), Slovakia (8), Finland (5), North Macedonia (8), Albania (5) and Serbia (33).
The aggregate for EU_V includes data for 17 EU Member States (Belgium, Bulgaria, Czechia, Estonia, Ireland, Spain, Croatia, Italy, Cyprus, Latvia, Lithuania, Austria, Poland, Romania, Slovenia, Slovakia and Finland).
4.2. Unit of measure
mg O2 per litre.
4.3. Reference Period
Calendar year.
4.4. Accuracy - overall
Based on the data from WISE-6 reporting, annual mean concentrations are used as a basis in the indicator analyses. Unless the country reports aggregated data, the aggregation to annual mean concentrations is done by the EEA.
Automatic quality control procedures are applied both to the disaggregated and aggregated data, excluding data failing the tests from further analysis. In addition, a semi-manual procedure is applied, focusing on suspicious values having a major impact on the country time series and on the most recently reported data. This comprises e.g.:
- outliers;
- consecutive values deviating strongly from the rest of the time series;
- whole time series deviating strongly in level compared to other time series for that country and determinand;
- where values for a specific year are consistently far higher or lower than the remaining values for that country and determinand.
Such values are removed from the analysis and checked with the country.
For time series analyses, only complete series after inter/extrapolation are used. This is to ensure that the aggregated time series are consistent, i.e. including the same sites throughout. Inter/extrapolation of gaps up to 3 years are allowed, to increase the number of available time series. At the beginning or end of the data series, missing values are replaced by the first or last value of the original data series, respectively. In the middle of the data series, missing values are linearly interpolated. The selected time series are aggregated to country and European level by averaging across all sites for each year.
4.5. Source data
4.5.1. Source data - Organisation
EEA (Waterbase database)
4.5.2. Source data - Comment
Data source: EEA Waterbase database on Water Quality ICM.
Data provider: European Environment Agency (EEA)
5.1. Frequency of dissemination
5.1.1. Frequency of dissemination - Grade
Every year5.1.2. Frequency of dissemination - Comment
Indicator is updated annually.
5.2. Timeliness
5.2.1. Timeliness - Grade
T+2 years5.2.2. Timeliness - Comment
New data points are disseminated within two years after the reference year.
6.1. Reference area
6.1.1. Reference Area - Grade
< 75% EU MS or no EU aggregate6.1.2. Reference Area - Comment
Data are presented for all EU Member States except Denmark, Germany, Greece, France, Luxembourg, Hungary, Malta, Netherlands, Portugal and Sweden.
6.2. Comparability - geographical
6.2.1. Comparability - geographical - Grade
< 75% EU MS6.2.2. Comparability - geographical - Comment
Data comparability between EU Member States, respectively other presented countries, is limited due to monitoring programs, including methodology and spatio-temporal sampling density, varying from country to country. The reporting is voluntary so countries do not necessarily report all available data.
6.3. Coverage - Time
6.3.1. Time Coverage - Grade
> 10 years6.3.2. Time Coverage - Comment
Presented time series (aggregate changing according to the context EU_V) starts in 2000.
6.4. Comparability - over time
6.4.1. Comparability - over time - Grade
> 4 data points6.4.2. Comparability - over time - Comment
Length of comparable time series without methodological break is longer than 4 data points.
Only complete series after inter/extrapolation are presented.
A major revision is expected by the end of 2025.
7.1. Dissemination format - Publications
Analysis of indicator is presented in Eurostat's annual monitoring report on Sustainable development in the EU (progress towards SDGs in an EU context).
7.2. Dissemination format - online database
See table sdg_06_30
7.3. Dissemination format - other
Eurostat dedicated section on SDGs: Eurostat overview.
Copyrights: Eurostat Copyright/Licence Policy is applicable.
