Các quốc gia có mật độ dân số cao và sản lượng công nghiệp cao đòi hỏi một cách tiếp cận khác nhau từ những người khác chủ yếu là nông thôn và công nghiệp ít. Trong cùng một cách, các vùng khô hạn có thể đặt ưu tiên cao cho bảo tồn nước và tái sử dụng. Các khu vực khác có thể có để đối phó với những ảnh hưởng đa dạng phong phú của các thành phần nước thải có hiệu ứng có hại lâu dài, đôi khi tại các địa điểm rất xa từ điểm xả | derived from business and public administration and specify how a successful sector and performing organisations should be managed. Prioritising functions and setting mandates of organisations First of all the priority issues for water pollution control in the medium term with a planning horizon of 10-20 years need to be determined. Countries with a high population density and high industrial output require a different approach from others which are predominantly rural and less industrialised. In the same way arid regions may put a high priority on water conservation and re-use. Other regions may have to cope with the diverse effects of multifarious wastewater constituents that have long-term deleterious effects sometimes at locations very distant from the discharge point. For example the nutrients discharged by households along the Rhine River in Switzerland cause algal blooms along the Danish North Sea coast triggering oxygen deficiency and fish kills and polychlorinated biphenyls PCBs discharged in Europe may over a period of years accumulate in the fatty tissue of seals near the North Pole. Institutional arrangements must reflect environmental priorities. It is commonly assumed that water pollution control requires the same institutional arrangements as for water supply. However often this is not the case. In many countries domestic wastewater collection and treatment are administered within the same organisation as water supply for example in India Uganda China Brazil some regions Mozambique Yemen the Philippines and England and Wales. In other countries separate organisations have been created such as in Indonesia for the urban areas Colombia Argentina and most West African and Western European countries. The executive functions for large infrastructure development and for its management commonly fall with an engineering-based government department board authority or enterprise. These can take many forms see section . By contrast the executive .
