Definition of water pollution

Summary

Water pollution (or aquatic pollution) is the contamination of water bodies—such as lakes, rivers, oceans, reservoirs, and groundwater—that negatively affects how the water can be used. It is usually caused by human activities, when contaminants mix with water and change its condition in ways that harm ecosystems and reduce the services water provides (e.g., safe drinking water). A practical definition is the addition of substances or energy forms that directly or indirectly alter the nature of a water body so that its legitimate uses are negatively affected. Water is typically considered polluted when it is contaminated by anthropogenic (human-made) substances, meaning it may no longer be safe for uses like drinking or irrigation, or it can significantly impair the ability of aquatic life to survive and function. Pollution can take many forms, including toxic chemicals (such as oil, metals, plastics, pesticides, and industrial waste), changes in physical or chemical conditions (like pH shifts, low oxygen, increased temperature, turbidity, or salinity changes), and the introduction of pathogens. Contaminants can come from major sources such as sewage discharges, industrial activities, agricultural activities, and urban runoff (including stormwater).

Key Points

• 1

  Water pollution is the contamination of water bodies that negatively affects their legitimate uses.

• 2

  It is commonly driven by human activities and can involve toxic substances, altered water conditions, and pathogens.

• 3

  Contaminants typically enter water from sources such as sewage, industry, agriculture, and urban runoff (stormwater).