that BOD levels in European rivers have been reduced by 20–30 percent since the enactment of the directive, but that other pollution parameters such as nitrogen levels remained high. The reason is that much of the nitrogen pollution comes from non-point sources in agriculture, and the still insufficient nutrient removal by wastewater treatment plants. The eutrophication of the Baltic Sea, North Sea and considerable parts of the Mediterranean thus remains a "severe problem". The report also noted that it is estimated that more than 50 percent of the discharges into sensitive areas was not treated sufficiently. Even for non-sensitive areas, although the picture was less bleak, only 69% of the discharge received treatment and the 2000 deadline was not met by most member countries. 25 out of 556 cities in the EU still had no wastewater treatment system at all. The directive triggered substantial investment in sewage treatment throughout the EU. A controversial aspect of the directive is the requirement for all agglomerations with more than 2,000 inhabitants to have a wastewater collection system, which has been widely interpreted as requiring connection to a sewer system even if existing on-site sanitation systems perform adequately. The cost of connecting houses to sewers in small rural towns with dispersed housing patterns is often very high and imposes a high financial burden on users. According to the European Commission, the directive represents the most cost intensive European legislation in the environmental sector. The EU estimates that the equivalent of €152 billion were invested in wastewater treatment from 1990 to 2010. The EU provides support for the implementation of the directive in the order of 5 billion Euro per year. Planned revision The European Commission is currently undergoing a consultation on the Urban Waste Water Treatment Directive. As the directive was adopted in 1991, its challenge will be to integrate the commitments taken with the Paris agreement as the wastewater treatment sector consumes 1% of the global total energy consumption. Under a business as usual scenario, this figure is expected to increase by 60% by 2040 compared to 2014. With the introduction of energy efficiency requirements, the energy consumption of the wastewater treatment sector can be reduced by 50% only by using current technologies. On top of that, there are also opportunities to produce enough energy from wastewater to turn the whole water sector energy neutral. It uses the energy embedded in the sludge