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Urban waste water treatment in Europe

Indicator Assessment
Prod-ID: IND-15-en
  Also known as: WAT 005
Created 29 Nov 2007 Published 29 Jan 2009 Last modified 21 Jan 2019
13 min read
This is an old version, kept for reference only.

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This page was archived on 24 Aug 2017 with reason: A new version has been published
Wastewater treatment in all parts of Europe has improved during the last 15-20 years. The percentage of the population connected to wastewater treatment in the southern, south-eastern and eastern Europe has increased during last ten years, but is still relative low compared to the central and northern Europe.

Key messages

Wastewater treatment in all parts of Europe has improved during the last 15-20 years. The percentage of the population connected to wastewater treatment in the southern, south-eastern and eastern Europe has increased during last ten years, but is still relative low compared to the central and northern Europe.

How effective are policies to improve urban waste water treatment at reducing discharges of nutrients and organic matter into surface waters in Europe?

Changes in wastewater treatment in regions of Europe between 1990 and 2005

Note: Only countries with data from (almost) all periods were included, the numbers of countries are given in parentheses

Data source:

EEA-ETC/WTR based on country data reported to OECD/EUROSTAT Joint Questionnaire. Data are available at Eurostat data tables.

Downloads and more info

Changes in wastewater treatment in northern countries of Europe between 1980s and 2005

Note: N/A

Data source:

EEA-ETC/WTR based on country data reported to OECD/EUROSTAT Joint Questionnaire. Data are available at Eurostat data tables.

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Changes in Changes in wastewater treatment in countries of Europe between 1980s and 2005 (Western)

Note: N/A

Data source:

EEA-ETC/WTR based on country data reported to OECD/EUROSTAT Joint Questionnaire. Data are available at Eurostat data tables.

Downloads and more info

Changes in wastewater treatment in countries of Europe between 1980s and 2005 (Southern)

Note: N/A

Data source:

EEA-ETC/WTR based on country data reported to OECD/EUROSTAT Joint Questionnaire. Data are available at Eurostat data tables.

Downloads and more info

Changes in wastewater treatment in countries of Europe between 1980s and 2005 (East)

Note: N/A

Data source:

EEA-ETC/WTR based on country data reported to OECD/EUROSTAT Joint Questionnaire. Data are available at Eurostat data tables.

Downloads and more info

Changes in wastewater treatment in countries of Europe between 1995 and 2005 (South-Eastern)

Note: N/A

Data source:

EEA-ETC/WTR based on country data reported to OECD/EUROSTAT Joint Questionnaire. Data are available at Eurostat data tables.

Downloads and more info

The main objective of the Urban Waste Water Treatment (UWWT) Directive is to protect the environment from the adverse effects of urban waste water discharges and discharges from certain industrial sectors and the measures concerns the collection, treatment and discharge of most of the waste water.

As a rule, the UWWT Directive provides for biological waste water treatment (secondary treatment), and thus a drastic reduction of the biodegradable pollution in waste water - which otherwise would severely impact on oxygen balance and ecosystems of our waters. In the catchments of particularly sensitive waters (sensitive areas), such as those suffering from eutrophication, more stringent treatment measures are required, to additionally eliminate nutrient pollution (nitrogen and phosphorus) from waste water (tertiary treatment).

 

The success indicators used in this assessment to measure the reduction in discharges of nutrients and organic matter from urban waste water to European surface waters are:

1. Percentage of population connected to waste water treatment.

2. Percentage of waste water given tertiary treatment.

 

1. Percentage of population connected to waste water treatment (Fig. 1 and the individual countries in Fig. 2-6). In northern and also in southern European countries more than 80 % of the population is connected to waste water treatment. In sparcely populated countries with a relative high proportion of the population living in scattered dwellings these dwelling are not connected to collecting systems and normally served by individual waste water treatment (e.g. septic tanks). In central Europe more than 90 % is connected. In eastern Europe only 50 % is connected (last data are from 2002, so this percentage may be higher now), whereas in south-eastern Europe (Turkey, Bulgaria and Romania) there is only 35 % that are connected to waste water treatment plants.

 

2. Percentage of waste water given tertiary treatment (yellow color on Fig. 1 to 6). Most of the population in the northern countries is connected to waste water treatment plants with the highest levels of treatment (tertiary), which efficiently removes nutrients (phosphorus or nitrogen or both) and organic matter. More than half of the waste water in central European countries is subject to tertiary treatment. In southern and eastern Europe only 20 % get tertiary treatment. Around half of the wastewater in southern European countries and 25 % in eastern Europe receive only secondary treatment. In south-eastern Europe the level of tertiary treatment is minor (< 5 %), whereas 20 % is subject to secondary treatment.

 

What levels of urban waste water treatment are applied in 'big cities' in the EU?

Number of EU15 agglomerations of more than 150 000 p.e. by treatment level, situation on 1st January 2003.

Note: N/A

Data source:

DGENV 2007

Downloads and more info

The lastest from 2007 EU Commissions Urban Waste Water Treatment (UWWT) Directive implementation report  can be found on http://ec.europa.eu/environment/water/water-framework/implrep2007/index_en.htm. According to this report waste water treatment in 349 out of the 571 big cities of Europe complied with the treatment requirements of the UWWT Directive without any need for updating the treatment. 122 of the 571 big cities with population equivalent more than 150 000 did not have a sufficient standard of treatment on 1st of January 2003 to meet the objectives of the UWWT Directive. 17 had no treatment at all. No information is available for four cities. These big cities account for 55% of the total waste water pollution load of organic matter covered by the 1998 and 2000 UWWT Directive deadlines (i.e. of > 470 mil. p.e.). 

 

Further information can be found in the WISE section on Urban Waste Water Treatment Directive http://www.eea.europa.eu/themes/water/water-pollution/prevention-strategies/urban-waste-water-treatment-directive.

 

Specific assessments of waste water treatment in different countries:

Northern Europe: Most of the waste water (80%) in Finland, Sweden and Norway receives tertiary treatment (Fig. 2), while in Iceland the waste water from half of the population is not treated at all and the other half only receive primary treatment. The trends in the rate of national population connected to the UWWTPs are affected by changes in the ratio of rural/urban population as well as by increasing use of separate individual treatment plants in rural areas.

 

Central Europe: In Switzerland, Germany, Denmark, Austria and the Netherlands most of the population is connected to the tertiary treatment (Fig. 3). In Ireland more than 30 % has no treatment at all and more than 40 % of waste water receives only primary treatment. In Belgium more than 60 % of the population had no treatment at all at the time of the last reporting (1998), but national state of the environment reports indicate marked improvement in waste water treatment over the last decade.

 

Southern Europe: The best situation is in Spain where more than 90% of population is connected to treatment systems (fig. 4). The worst situation is in Malta, where almost 90 % of population has no treatment of their waste water at all. In France 80 % is connected, whereas the percentage connected to waste water treatment in Italy, Greece and Portugal is higher than 60 %,  higher than  50 % and ca. 40 %, respectively. Tertiary treatment is minor in this region in general with maximum 20 % of the total waste water (Italy, France and Spain), and less than 10 % in Greece and Portugal

 

Eastern Europe:  More than 65 % of the population in the Czech Republic, Estonia, Latvia and Lithuania is connected to the waste water treatment, and roughly half of the waste water connected to treatment systems is given tertiary treatment (fig. 5). For Poland and Hungary around 60 % of the population is connected to waste water treatment systems. In Poland about half of the connected wastewater are given tertiary treatment, whereas in Hungary only 10 % gets tertiary treatment. The worst situation is in Slovenia, where almost 70 % of the population is not connected to waste water treatment systems. For Slovakia there is no detailed information on treatment type available.

 

South-Eastern Europe: In south eastern European countries (Turkey, Bulgaria, Romania) only around 40% of the population is connected to the waste water treatment, with most of the connected waste water receiving only secondary or primary treatment (fig. 6). Only in Turkey there is a small proportion of the waste water that receives tertiary treatment.

 

Indicator specification and metadata

Indicator definition

The indicator on urban waste water treatment, WAT005, collects data on the percentage of the population connected to sewage collection systems, as well as on the prevalence of primary, secondary and tertiary urban waste water treatment plants.

The amount of urban waste water treated from 'big cities' is expressed as population equivalents (p.e.).

The indicator illustrates:

  1. urban waste water collection and treatment in Europe in 2017;
  2. the development of more stringent (tertiary) urban waste water treatment practice;
  3. the level of urban waste water treatment in 'big cities (agglomerations of > 150 000 p.e.) in the EU.

Units

The percentages of the population connected to primary, secondary and tertiary urban waste water treatment facilities (Figures 1 and 2).

The percentage of population equivalent (p.e.) was used for “big city” treatment (Figure 3).


Policy context and targets

Context description

The main objective of the Urban Waste Water Treatment Directive (91/271/EEC) (UWWTD), and equivalent national legislation for non-EU countries, is to protect surface waters from the adverse effects of waste water discharges. The UWWTD prescribes the level of treatment required before discharge to surface waters. It requires Member States to provide all urban settlements (called 'agglomerations' in the UWWTD) of more than 2 000 p.e. with collecting systems. Primary (mechanical) and secondary (i.e. biological) treatments must be provided for all agglomerations of more than 2 000 p.e. that discharge into fresh waters. Special requirements, with intermediate deadlines depending on the sensitivity of the receiving waters, are placed on urban settlements of more than 10 000 p.e., with various size classes. The performance of the treatment is assessed using several determinands (biochemical oxygen demand (BOD) and chemical oxygen demand (COD); plus total nitrogen and total phosphorus in the case of more stringent treatment).

For urban settlements smaller than those described above and equipped with a collecting system, the treatment must be 'appropriate', meaning that the discharge must allow the receiving waters to meet the relevant quality standards.

The UWWTD, adopted in 1991, is also a basic measure under the Water Framework Directive (WFD). The WFD requires the estimation and identification of significant point- and diffuse-source pollution, in particular by the substances listed in Annex VIII, from urban, industrial, agricultural and other installations and activities, based, inter alia, on information gathered, for instance, under Articles 15 and 17 of the UWWTD. Based on the substances listed in Annex VIII WFD, the following are important for this indicator:

  • substances that have an unfavourable influence on oxygen balance (and can be measured using parameters such as BOD, COD, etc.);
  • materials in suspension;
  • substances that contribute to eutrophication (in particular nitrates and phosphates).

Member States should thus take the necessary steps to collect these data. Reducing pollutants stemming from waste water is one of the key challenges of reaching good ecological and good chemical status of surface waters, as required by the WFD.

Collecting and treating waste water has required huge investment across Europe in recent decades. The kinds of new challenges facing urban waste water treatment, such as climate change, resource efficiency and improved environmental protection, are set out in the EEA briefing Urban waste water treatment for 21st century challenges.

Further information on emissions from industry to water, including to urban waste water treatment plants, is available in Industrial waste water treatment - pressures on Europe's environment.

Targets

The UWWT Directive (91/271/EEC) aims to protect the environment from the adverse effects of urban waste water discharges. It prescribes the level of treatment required before discharge and should have been fully implemented in the EU-15 countries by 2005. For the newer Member States (i.e. the EU-13), staged transition periods were set within the Accession Treaties which, in principle, did not extend beyond 2015. However, in Romania, smaller agglomerations (with less than 10 000 p.e.) should have complied with the directive by the end of 2018, and Croatia has different transition periods, from 2018 to 2023.

Under the directive, EU-15 Member States were required to provide all urban settlements of more than 2 000 p.e. with collecting systems and all waste waters collected had to be provided with appropriate treatment by 2005. Secondary treatment (i.e. biological treatment) must be provided for all urban settlements of more than 2 000 p.e. that discharge into fresh waters, while more advanced treatment (tertiary treatment) is required for discharges into sensitive areas.


The achievements resulting from the UWWTD should be seen as an integral part of achieving good status for all waters under the WFD. 

 

        

Related policy documents

Methodology

Methodology for indicator calculation

The indicator is based on data from Eurostat, which show the percentage of the population connected to each treatment type. Compared with previous versions of the indicator, Figure 1 now shows the treatment level in EEA member and cooperating countries in 2017, rather than grouping countries according to region.

A p.e. of 1 is equivalent to an organic biodegradable load having a 5-day BOD of 60 g per day.

Tertiary treatment is known in the UWWT Directive as 'treatment more stringent than secondary' and includes the application of secondary treatment.

'Big cities' is a term used in the UWWT Directive for cities of at least 150 000 p.e. or agglomerations responsible for large waste water discharges. Countries themselves identify their 'big cities'.

Methodology for gap filling

Gap filling was undertaken on the basis that once an urban waste water infrastructure had been put in place, it was likely to be used in subsequent years. Therefore, any gaps were filled with data from the most recent year reported, e.g. 2016 data carried forward to 2017. This approach was used for up to 5 years of gap filling, i.e. 2012 data could be carried forward to up to 2017.

 

Methodology references

  • Eurostat Water statistics on national level (env_nwat) Yearly data on freshwater resources, water abstraction and use, connection rates of resident population to wastewater treatment, sewage sludge production and disposal, generation and discharge of wastewater collected biennially by means of the OECD/Eurostat Joint Questionnaire - Inland Waters. Data aggregation: national territories.

Uncertainties

Methodology uncertainty

The main uncertainties relate to data reported to Eurostat. In 2005, treatment for 24 % of the population was 'unknown', which fell to 15 % in 2017.  The second area of uncertainty relates to numbers of inhabitants, as these do not necessarily align with reported population data, though error here is generally small.

The 'EU-27' value is strongly influenced by the situation in Member States with large populations (France, Germany, Italy and Spain).  

At country level, the population figure and the generated p.e. load are not usually the same, as there can be other sources of organic pollution, such as food industry and temporal changes in population owing e.g. to tourism.

Data sets uncertainty

Data reported to Eurostat sometimes provide an incomplete picture of inhabitants connected to waste water treatment (e.g. the percentage of the population connected to urban waste water systems is given, but the percentage for which the waste water is collected without treatment is missing).

'Big cities' data sometimes include data from agglomerations that are much smaller than 150 000 p.e. However, the impact of such errors on the final percentages is rather small.

 

 

Rationale uncertainty

Data from the UWWT Directive focuses on the performance of the treatment plant and of the agglomeration. However, urban waste water treatment systems could also include sewer networks with storm water overflows and storage, which are complex and therefore overall performance is difficult to assess. In addition to the treatments covered by the UWWT Directive, there are other possible treatments, mostly industrial, but also independent treatments of smaller settlements outside urban agglomerations not included in UWWT Directive reporting. Compliance with the levels defined in the directive therefore does not guarantee that there is no pollution due to urban waste water.

In addition, urban waste water treatment (primary, secondary or tertiary, as described above) is the main waste water treatment used across the EEA area, but there are other possible treatments classified as 'Other Waste Water Treatment', which are mostly industrial or independent treatments. Furthermore, there are differences in how countries have interpreted the definitions of different classes of treatment (classes based on performance or design capacity and tertiary treatment for nitrogen, phosphorus or organic matter) that, in turn, lead to differences in the level of purification attributed by the countries to the different classes. These differences emphasise the problem of using types of treatment plant as a proxy for the level of purification.

 

 

Data sources

Metadata

Topics:

information.png Tags:
, , , , , , ,
DPSIR: Response
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)

Dates

Frequency of updates

Updates are scheduled every 3 years

EEA Contact Info

Caroline Whalley