Introduction
Water pollution is one of the most pressing global environmental issues, and in IB Environmental Systems and Societies (ESS), it plays a central role in the 2026 first assessment. Students are expected to understand not only the types and causes of pollution, but also how pollution impacts ecosystems, societies, and sustainability.
This topic often appears in exams because it allows for systems thinking: linking pollution sources, impacts on biodiversity, human health consequences, and management strategies. To score highly, you need to go beyond definitions—using examples, evaluations, and case studies to demonstrate applied knowledge.
Quick Start Checklist for ESS Students
When revising water pollution for ESS, you should be able to:
- Define different types of water pollution.
- Identify sources (point vs. non-point).
- Explain impacts on ecosystems and human health.
- Use case studies to illustrate consequences.
- Evaluate management and prevention strategies.
Types of Water Pollution in ESS
1. Organic Pollution
- Sources: sewage, animal waste, food processing industries.
- Impacts: increases Biochemical Oxygen Demand (BOD), reduces dissolved oxygen, kills aquatic life.
- Example: untreated sewage in the Ganges River, India.
2. Nutrient Pollution (Eutrophication)
- agricultural runoff (nitrates, phosphates), detergents.
