Water pollution — overview

Water is a key resource for our quality of life, the things we grow and produce. It also provides natural habitats and eco-systems for Europe’s plant and animal species.

Access to clean water for drinking and sanitary purposes is a precondition for human health and well-being. Most people in Europe have access to drinking water of good quality. However, in some parts the quality still frequently does not meet basic biological and chemical standards. Clean unpolluted water is also essential for our ecosystems. Plants and animals in lakes, rivers and seas react to changes in their environment caused by changes in chemical water quality and physical disturbance of their habitat. Changes in species composition of organism groups like phytoplankton, algae, macrophytes, bottom-dwelling animals and fish can be caused by changes in the climate. They can also indicate changes in water quality caused by eutrophication, organic pollution, hazardous substances or oil. Changes in habitats can result from the physical disturbance through damming, channelisation and dredging of rivers, construction of reservoirs, sand and gravel extraction in coastal waters, bottom trawling by fishing vessels etc.

Almost all human activities can and do impact adversely upon the water. Water quality is influenced by both direct point source and diffuse pollution which come from urban and rural populations, industrial emissions and farming. Diffuse pollution from farming and point source pollution from sewage treatment and industrial discharge are principal sources. For agriculture, the key pollutants include nutrients, pesticides, sediment and faecal microbes. Oxygen consuming substances and hazardous chemicals are more associated with point source discharges.

The diagram illustrates the many sources of nitrogen pollution in water. Generally, a distinction can be made between:

• point sources, such as discharges from urban wastewater, industry and fish farms; 
• diffuse sources, such as background losses (e.g. forests), losses from agriculture, losses from scattered dwellings and atmospheric deposition on water bodies (e.g. marine areas or lakes).

Source: Ærtebjerg et al. (2003).

The following pages describe:

• Point sources
• Diffuse sources
• Prevention strategies