Reference metadata describe statistical concepts and methodologies used for the collection and generation of data. They provide information on data quality and, since they are strongly content-oriented, assist users in interpreting the data. Reference metadata, unlike structural metadata, can be decoupled from the data.
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, 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. DG 15 seeks to protect, restore and promote the conservation and sustainable use of terrestrial, inland water and mountain ecosystems.
The indicator can be considered as part of the 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. 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
This indicator measures the concentration of phosphate (PO4) per litre in the dissolved phase from water samples from river stations and aggregated to annual average values. At high concentrations phosphate can cause water quality problems, such as eutrophication, by triggering the growth of aquatic plants including algae. The indicator can be used to illustrate geographical variations in current nutrient concentrations and temporal trends.
For time series analyses, only complete series after inter/extrapolation are presented. As measuring stations change over time, this leads to a recalculation of the whole indicator with each update. Complete series 2000 – 2022 are based on a total of 669 monitoring sites in rivers (581 within 15 EU Member States). These river sites are distributed over the following countries (number of sites in parentheses): Belgium (28), Bulgaria (52), Czechia (8), Denmark (39), Estonia (37), Ireland (33), Spain (43), Croatia (16), Italy (18), Latvia (16), Lithuania (22), Romania (87), Slovakia (6), Finland (66), Sweden (110), Iceland (1), Norway (18), Switzerland (16), North Macedonia (17), Albania (3) and Serbia (33).
The aggregate for EU_V include data for the following 15 EU Member States: Belgium, Bulgaria, Czechia, Denmark, Estonia, Ireland, Spain, Croatia, Italy, Latvia, Lithuania, Romania, Slovakia, Finland and Sweden.
4.2. Unit of measure
mg PO4 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 year
5.1.2. Frequency of dissemination - Comment
The indicator is updated annually.
5.2. Timeliness
5.2.1. Timeliness - Grade
T+2 years
5.2.2. 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 aggregate
6.1.2. Reference Area - Comment
Data are presented for all EU Member States except Germany, Greece, France, Cyprus, Luxembourg, Hungary, Malta, Netherlands, Austria, Poland, Portugal and Slovenia.
6.2. Comparability - geographical
6.2.1. Comparability - geographical - Grade
< 75% EU MS
6.2.2. Comparability - geographical - Comment
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 overall accuracy under point 4.4.
6.3. Coverage - Time
6.3.1. Time Coverage - Grade
> 10 years
6.3.2. 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 points
6.4.2. Comparability - over time - Comment
Length of comparable time series without methodological break is longer than 4 data points.
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 the EU context).
This indicator measures the concentration of phosphate (PO4) per litre in the dissolved phase from water samples from river stations and aggregated to annual average values. At high concentrations phosphate can cause water quality problems, such as eutrophication, by triggering the growth of aquatic plants including algae. The indicator can be used to illustrate geographical variations in current nutrient concentrations and temporal trends.
For time series analyses, only complete series after inter/extrapolation are presented. As measuring stations change over time, this leads to a recalculation of the whole indicator with each update. Complete series 2000 – 2022 are based on a total of 669 monitoring sites in rivers (581 within 15 EU Member States). These river sites are distributed over the following countries (number of sites in parentheses): Belgium (28), Bulgaria (52), Czechia (8), Denmark (39), Estonia (37), Ireland (33), Spain (43), Croatia (16), Italy (18), Latvia (16), Lithuania (22), Romania (87), Slovakia (6), Finland (66), Sweden (110), Iceland (1), Norway (18), Switzerland (16), North Macedonia (17), Albania (3) and Serbia (33).
The aggregate for EU_V include data for the following 15 EU Member States: Belgium, Bulgaria, Czechia, Denmark, Estonia, Ireland, Spain, Croatia, Italy, Latvia, Lithuania, Romania, Slovakia, Finland and Sweden.
15 April 2025
Not Applicable
Not Applicable
Not Applicable
Calendar year.
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.
