--- title: "Water pollution: sources and effects" subject: "Environment and Pollution Control" chapter: 4 key: "semester_7/environment_and_pollution_control:water-pollution-sources-effects" source: https://www.bctengineer.com/q/semester_7/environment_and_pollution_control/water-pollution-sources-effects site: BCT Engineering --- # Water pollution: sources and effects Environment and Pollution Control · Chapter 4: Water pollution - Asked in: year not given, 5 marks - Video: [Water Pollution](https://www.youtube.com/watch?v=GNGKsubYJ9U) — Bozeman Science - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_7/environment_and_pollution_control/water-pollution-sources-effects - Whole chapter: https://www.bctengineer.com/md/semester_7/environment_and_pollution_control/chapter-4 ## Question Define water pollution. Describe the major sources and types of water pollutants and their effects on human health and aquatic life. ## Short answer Water pollution is contamination of water bodies by substances harmful to humans and aquatic life. Point sources like sewage and industrial effluents introduce pathogens, organic matter, heavy metals; non‑point runoff adds nutrients and pesticides. Effects include waterborne diseases, oxygen depletion, eutrophication and bioaccumulation of toxics. ## Answer Water pollution is the contamination of water bodies (rivers, lakes, groundwater, oceans) by substances that degrade its quality and make it unfit for its intended use, harming humans and aquatic life. #### Sources - **Point sources:** discharge from a specific location: sewage outfalls, industrial effluents (tannery, textile, distillery, paper), hospital waste. - **Non-point sources:** diffuse runoff from agricultural land (fertilizer, pesticides), urban storm water, mining areas and open dumping. #### Types of pollutants and their effects | Pollutant | Source | Effect | |---|---|---| | Pathogens (bacteria, viruses, protozoa) | Untreated sewage, animal waste | Cholera, typhoid, dysentery, hepatitis | | Oxygen-demanding organic matter | Sewage, food industries | Fall of dissolved oxygen; fish kill; odour | | Nutrients (N, P) | Fertilizer, detergents, sewage | Eutrophication, algal blooms, nitrate in drinking water (blue baby syndrome) | | Heavy metals (Pb, Hg, Cd, As) | Mining, batteries, industries | Toxic, bioaccumulate (Minamata, Itai-itai); arsenic in groundwater | | Toxic organics (pesticides, PCBs) | Agriculture, industry | Cancer, biomagnification in food chains | | Suspended solids / sediment | Erosion, construction | Turbidity, reduced light, siltation | | Heat | Power plant cooling water | Lower oxygen solubility, harm to fish | | Acids / alkalis | Industry, mine drainage | Change of pH, harm to aquatic life | Water-borne diseases are the main health burden in developing countries; the aquatic ecosystem suffers from oxygen depletion, loss of species and eutrophication. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Which is a non-point source of water pollution? A. Sewage outfall pipe B. Tannery effluent C. Agricultural runoff of fertilizer D. Hospital waste discharge Answer: C. Non-point sources are diffuse, such as farm and urban runoff; outfalls and effluents are point sources. (Key point: Point vs non-point) 2. Nutrients N and P in water cause: A. Eutrophication and algal blooms B. Increased dissolved oxygen only C. Biomagnification D. Siltation Answer: A. Fertilizer, detergents and sewage nutrients cause algal blooms and eutrophication. (Key point: Eutrophication) 3. What does organic matter in sewage do to a river? A. Raises DO B. Lowers dissolved oxygen, causing fish kills C. Raises pH D. Lowers turbidity Answer: B. Bacteria consume oxygen while decomposing the organic matter, so DO falls. (Key point: Oxygen-demanding waste) 4. Why does heated cooling water harm fish? A. It lowers oxygen solubility B. It increases oxygen C. It adds nutrients D. It reduces pH to zero Answer: A. Warm water holds less dissolved oxygen. (Key point: Thermal pollution) ## Related in Environment and Pollution Control - [Particulate pollutants: sources and effects](https://www.bctengineer.com/question.md?key=semester_7%2Fenvironment_and_pollution_control%3Aparticulate-pollutants-sources-effects) — Environment and Pollution Control, chapter 1 - [Indoor air pollutants and their sources](https://www.bctengineer.com/question.md?key=semester_7%2Fenvironment_and_pollution_control%3Aindoor-air-pollutants-sources) — Environment and Pollution Control, chapter 3 - [Sources and effects of SO2, NOx and CO](https://www.bctengineer.com/question.md?key=semester_7%2Fenvironment_and_pollution_control%3Agaseous-pollutants-so2-nox-co) — Environment and Pollution Control, chapter 1 - [Household smoke pollution and effects on residents](https://www.bctengineer.com/question.md?key=semester_7%2Fenvironment_and_pollution_control%3Ahousehold-smoke-pollution-effects) — Environment and Pollution Control, chapter 3 - [Classification and sources of air pollutants](https://www.bctengineer.com/question.md?key=semester_7%2Fenvironment_and_pollution_control%3Aair-pollutants-classification-sources) — Environment and Pollution Control, chapter 1 ## Related in other subjects - [Water pollution, pollutants and adverse effects](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Awater-pollutants-effects) — Engineering Chemistry, chapter 3 - [Sources, effects and remedies of water pollution](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Awater-pollution-sources) — Engineering Chemistry, chapter 3, asked 2× - [Classification of air pollutants; sources, effects](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Aair-pollutants-classified) — Engineering Chemistry, chapter 3 - [Water pollutants, sources; oxides making water acidic](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Awater-pollutants-acidic) — Engineering Chemistry, chapter 3