Urban Waste Water Treatment Directive
The Urban Waste Water Treatment Directive 1991 (91/271/EEC) is a European Union directive concerning urban waste water "collection, treatment and discharge of urban waste water and the treatment and discharge of waste water from certain industrial sectors". It aims "to protect the environment from adverse effects of waste water discharges from cities and "certain industrial sectors".
Source: Wikipedia — Urban Waste Water Treatment Directive (CC BY-SA 4.0)