agglomeration — an area where the population and/or economic activities are sufficiently concentrated for urban waste water to be collected and conducted to an urban waste water treatment plant or to a final discharge point 4.

appropriate treatment — treatment of urban waste water by any process and/or disposal system which after discharge allows the receiving waters to meet the relevant quality objectives and the relevant provisions of this and other Community Directives 9.

coastal waters — the waters outside the low-water line or the outer limit of an estuary 13.

collecting system — a system of conduits which collects and conducts urban waste water 5.

domestic waste water — waste water from residential settlements and services which originates predominantly from the human metabolism and from household activities 2.

estuary — the transitional area at the mouth of a river between fresh-water and coastal waters. Member States shall establish the outer (seaward) limits of estuaries for the purposes of this Directive as part of the programme for implementation in accordance with the provisions of Article 17 (1) and (2) 12.

eutrophication — 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 11.

industrial waste water — any waste water which is discharged from premises used for carrying on any trade or industry, other than domestic waste water and run-off rain water 3.

primary treatment — treatment of urban waste water by a physical and/or chemical process involving settlement of suspended solids, or other processes in which the BOD5 of the incoming waste water is reduced by at least 20 % before discharge and the total suspended solids of the incoming waste water are reduced by at least 50 % 7.

secondary treatment — treatment of urban waste water by a process generally involving biological treatment with a secondary settlement or other process in which the requirements established in Table 1 of Annex I are respected 8.

Sludge — residual sludge, whether treated or untreated, from urban waste water treatment plants 10.

urban waste water — domestic waste water or the mixture of domestic waste water with industrial waste water and/or run-off rain water 1.