Topic explanation

Standard explanation

Water pollutants are chemical, biological or physical substances that reduce water quality or make water harmful or unsuitable for a particular use.

Key points

• Beginner: Water can look clear and still be polluted. It may contain germs or harmful dissolved chemicals that
• Intermediate: Pollutants should be identified by source, concentration and effect. Nutrients are necessary for lif
• Water pollutants may be chemical, biological or physical.
• Major examples include sewage, excess nutrients, toxic metals, pathogens, sediments and industrial chemicals.
• Effects depend on concentration, chemical form and interaction with aquatic systems.

Labelled diagram