This section presents key data related to the implementation of the Urban Waste Water Treatment Directive (UWWTD) in Europe. Country profiles are available for each EU-27 Member State, as well as for Norway and Iceland. The European Union profile presents similar information, aggregated to EU-27 level.
The Urban Waste Water Treatment Directive in a nutshell
Discharges of urban waste water to the environment may contain organic pollution, bacteria, viruses, nitrogen and phosphorus. Therefore, urban waste water needs to be treated adequately, before it is discharged.
In Europe, the treatment of urban waste water is regulated by the Council Directive 91/271/EEC concerning urban waste water treatment (UWWTD). A time plan has been set out for the construction of necessary infrastructure for collecting and treating waste water in agglomerations (urban areas), which generate more than 2 000 p.e. of waste water . In general , waste water must be subject to secondary treatment (biological treatment), which removes a very high proportion of organic pollution, bacteria and viruses. However, in catchments with sensitive waters, the urban areas that generate more than 10 000 p.e. of waste water are required to apply more stringent treatment with further removal of nitrogen and/or phosphorus. The removal of nitrogen and/or phosphorus protects sensitive waters from the risk of algal blooms.
The UWWTD sets common standards among countries for the concentrations of organic pollution, suspended solids, nitrogen and phosphorus in the discharges of treated urban waste water, as well as the necessary monitoring frequency. Each urban area that generates waste water more than 2 000 p.e. is assessed for its compliance with the UWWTD.
An urban area is considered to be compliant with the UWWTD requirements, when all generated waste water is collected and receives treatment in line with the UWWTD provisions.
Urban waste water treatment for 21st century challenges. EEA Briefing 2019
 “agglomeration” is an area where the population and/or economic activities are sufficiently concentrated for urban waste water to be collected/treated.
 “p.e.” stands for population equivalent, and it is a unit to measure the amount of waste water generated from a population of the mentioned size; e.g. 2 000 p.e. is the amount of waste water generated from a population of 2 000 people.
 This applies for areas considered as “normal” (an area of a Member State, which is not covered by sensitive area , its catchment or less sensitive area, is automatically considered as normal area). The requirements applied to either “sensitive” or “less sensitive” areas (e.g. coastal waters) are provided in the following summary table.