Statistical Office of the European Commission (Eurostat)

Unit E2: Environmental statistics and accounts; sustainable development

e-mail contact : ESTAT-SDG-MONITORING@ec.europa.eu

The 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 and SDG 15 on protecting, restoring and promoting sustainable use of land; which are embedded in the European Commission’s Priorities under the 'European Green Deal'. 

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.

This indicator measures the mean annual five-day biochemical oxygen demand (BOD5) in rivers, weighted by the number of measuring stations. BOD5 is a measure of the amount of oxygen that aerobic microorganisms need to decompose organic substances in a water sample over a five-day period in the dark at 20 °C. High BOD5 values are usually a sign of organic pollution, which affects water quality and the aquatic environment. Organic pollution caused by discharges from waste water 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 in this section stem from the 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 2000 – 2021 are based on a total of 715 monitoring sites (669 within 18 EU Member States) distributed over the following countries (number of monitoring sites in parentheses): Belgium (36), Bulgaria (73), Czechia (22), Estonia (35), Ireland (14), Spain (177), Croatia (23), Italy (44), Cyprus (4), Latvia (16), Lithuania (22), Austria (1), Poland (90), Romania (88), Slovenia (10), Slovakia (8), Finland (5), Sweden (1), North Macedonia (8), Albania (5) and Serbia (33). 

The aggregate for EU_V includes data for 18 EU Member States (Belgium, Bulgaria, Czechia, Estonia, Ireland, Spain, Croatia, Italy, Cyprus, Latvia, Lithuania, Austria, Poland, Romania, Slovenia, Slovakia, Finland and Sweden).

mg O₂ per litre.

Calendar year.

Indicator from non-ESS source. For assessment of accuracy please refer to the original source (see link to external data source and metadata in section “Annexes”).

The indicator is relative robust in presenting the overall trend and spatial variation in water quality, however, the distribution of monitoring sites might not be representative within the countries. A mean density of at least one monitoring site per 1 000 km2 is only achieved in Belgium; in all other countries, there is less than one monitoring site per 1 000 km2. In Austria, Sweden and Finland the number of monitoring sites is particularly low (more than 10 000 km2 per monitoring site). 

EEA (Waterbase database)

Data source: EEA Waterbase database on Water Quality ICM.

Data provider: European Environment Agency (EEA)

Every year

Indicator is updated annually.

T+2 years

< 75% EU MS or no EU aggregate

Data are presented for the EU Member States Belgium, Bulgaria, Czechia, Estonia, Ireland, Spain, Croatia, Italy, Cyprus, Latvia, Lithuania, Austria, Poland, Romania, Slovenia, Slovakia Sweden and Finland; plus North Macedonia, Albania and Serbia.

< 75% EU MS

The data for the reporting countries are only comparable within the limits of the weighting of the different number of samples per country. See also point 4.4 on the overall accuracy.

Furthermore, most countries measure organic matter as BOD over five days but a few countries measure BOD over seven days, which may introduce a small uncertainty in comparisons between countries.

> 10 years

Presented time series starts in 2000.

> 4 data points

Length of comparable time series without methodological break is longer than 4 data points.

Analysis of indicator is presented in Eurostat's annual monitoring report on Sustainable development in the EU (progress towards SDGs in an EU context).

See table sdg_06_30

Eurostat dedicated section on SDGs: http://ec.europa.eu/eurostat/web/sdi/overview

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