• 31 December 1998: all agglomerations of more than 10 000 “population equivalent”* (p.e.) which discharge their effluent into sensitive areas must have a proper collection and treatment system;
• 31 December 2000: all agglomerations of more than 15 000 p.e. which do not discharge their effluent into a sensitive area must have a collection and treatment system which enables them to satisfy the requirements in Table 1 of Annex I;
• 31 December 2005: all agglomerations of between 2 000 and 10 000 p.e. which discharge their effluent into sensitive areas, and all agglomerations of between 2 000 and 15 000 p.e. which do not discharge into such areas must have a collection and treatment system.

Annex II requires Member States to draw up lists of sensitive and less sensitive areas which receive the treated waters. These lists must be updated regularly.

The treatment of urban water is to be varied according to the sensitivity of the receiving waters.

The Directive lays down specific requirements for discharges from certain industrial sectors of biodegradable industrial waste water not entering urban waste water treatment plants before discharge to receiving waters.

Member States are responsible for monitoring both discharges from treatment plants and the receiving waters. They must ensure that the competent national authorities publish a situation report every two years. This report must also be sent to the Commission.

Member States must set up national programmes for the implementation of this Directive and must present them to the Commission.

The Directive also provides for temporary derogations.

Directive 98/15/EC
This Directive clarifies the rules relating to discharges from urban waste water treatment plants in order to put an end to differences in interpretation by the Member States.

It specifies, among other things, that:

• the option of using daily averages for the total nitrogen concentration applies both to agglomerations of 10 000-100 000 p.e. and to those of more than 100 000 p.e.;
• the condition concerning the temperature of the effluent in the biological reactor and the limitation on the time of operation to take account of regional climatic conditions only apply to the “alternative” method using daily averages;
• use of the “alternative” method must ensure the same level of environmental protection as the annual mean technique.

Key terms used in the act
• urban waste water means waste water from residential settlements and services which originates predominantly from the human metabolism and from household activities (domestic waste water) or a mixture of domestic waste water with waste water which is discharged from premises used for carrying on any trade or industry (industrial waste water) and/or run-off rain water;
• eutrophication means the enrichment of water by nutrients, especially compounds of nitrogen and/or phosphorus, causing an accelerated growth of algae and higher forms of plant life to produce an undesirable disturbance to the balance of organisms present in the water and to the quality of the water concerned;
• population equivalent is a measure of pollution representing the average organic biodegradable load per person per day: it is defined in Directive 91/271/EEC as the organic biodegradable load having a five-day biochemical oxygen demand (BOD5) of 60 g of oxygen per day.