---
title: "Water pollution"
subject: "Engineering Chemistry"
chapter: 3
key: "semester_2/engineering_chemistry:water-pollution-familiarity"
source: https://www.bctengineer.com/q/semester_2/engineering_chemistry/water-pollution-familiarity
site: BCT Engineering
---

# Water pollution

Engineering Chemistry · Chapter 3: Environmental Chemistry

- Asked in: 2070 Bhadra, 3 marks
- Video: [What Is Water Pollution | Environmental Chemistry | Chemistry | FuseSchool](https://www.youtube.com/watch?v=Zk1J2EW-nmQ) — FuseSchool - Global Education
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_2/engineering_chemistry/water-pollution-familiarity
- Whole chapter: https://www.bctengineer.com/md/semester_2/engineering_chemistry/chapter-3

## Question

Give your familiarity with water pollution.

## Short answer

Water pollution is contamination of water bodies by sewage, industrial effluents, and agricultural runoff with pathogens, heavy metals, and nutrients. It causes cholera, Minamata disease, arsenicosis, eutrophication, and biomagnification. Control measures include wastewater treatment, controlled agrochemical use, and public awareness.

## Answer

**Water pollution** is the contamination of water bodies (rivers, lakes, groundwater) by substances in such amounts that it becomes harmful to living things and unfit for use.

**Sources:** domestic sewage, industrial effluents, agricultural runoff of fertilisers and pesticides, mining, oil spills, thermal discharge and solid waste dumping.

**Pollutants:** pathogens, organic wastes, heavy metals (Pb, Hg, Cd, As), nitrates and phosphates, detergents, oils and heat.

**Effects:** waterborne diseases (cholera, typhoid), Minamata disease (Hg), arsenicosis, eutrophication with oxygen depletion and fish kills, and bioaccumulation.

**Control:** treatment of sewage and industrial effluent, controlled use of agrochemicals, banning dumping of waste in rivers, and public awareness.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Water pollution is
   A. Contamination of water bodies so that it harms living things and is unfit for use
   B. Natural purification
   C. Water with dissolved oxygen
   D. Drinking water treatment
   Answer: A. Harmful substances make water unfit. (Key point: Definition)

2. Which is an agricultural source of water pollution?
   A. Hot cooling water from power plants
   B. Runoff of fertilisers (nitrates, phosphates), pesticides and animal wastes
   C. Acid mine drainage
   D. Tannery effluents with phenols
   Answer: B. Agricultural runoff carries fertilisers, pesticides and animal wastes; the others are thermal, mining and industrial sources. (Key point: Sources)

3. How does excess nitrate and phosphate in a lake kill fish?
   A. They make the water too alkaline for fish gills
   B. They directly poison fish with nitrate crystals
   C. They cause algal bloom; on decay the algae use up dissolved oxygen (high BOD, low DO)
   D. They raise dissolved oxygen so much that fish burst
   Answer: C. Nutrients cause algal bloom; decay of the algae consumes dissolved oxygen, so fish suffocate. (Key point: Eutrophication)

4. Which is a key remedy for water pollution from sewage and industry?
   A. Discharge them directly into rivers so they dilute
   B. Add more phosphate detergents
   C. Dump solid waste into rivers so it settles
   D. Treat sewage and industrial effluents (primary, secondary, tertiary) before discharge
   Answer: D. Treating effluents before discharge removes pollutants at the source. (Key point: Effluent treatment)

## Related in Engineering Chemistry

- [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×
- [Sources and impacts of water pollution](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Awater-sources-impacts) — Engineering Chemistry, chapter 3
- [Sources of water pollution](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Awater-sources) — Engineering Chemistry, chapter 3
- [Water pollution, pollutants and adverse effects](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Awater-pollutants-effects) — Engineering Chemistry, chapter 3
- [Organic/inorganic water pollutants, effects, remedies](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Awater-pollution-substances-effects-remedies) — Engineering Chemistry, chapter 3, asked 2×
- [Point and non-point sources; waste water treatment](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Apoint-nonpoint-waste-water) — Engineering Chemistry, chapter 3

## Related in other subjects

- [Water pollution: sources, causes and impacts](https://www.bctengineer.com/question.md?key=semester_7%2Ftechnology_environment_and_society%3Awater-pollution-sources-impacts) — Technology, Environment and Society, chapter 5
- [Water pollution and fecal-oral route](https://www.bctengineer.com/question.md?key=semester_7%2Ftechnology_environment_and_society%3Awater-pollution-fecal-oral) — Technology, Environment and Society, chapter 5
- [Inorganic water pollution in Nepal](https://www.bctengineer.com/question.md?key=semester_7%2Ftechnology_environment_and_society%3Ainorganic-water-pollution-nepal) — Technology, Environment and Society, chapter 5
- [Water and air pollution in Nepal](https://www.bctengineer.com/question.md?key=semester_7%2Ftechnology_environment_and_society%3Awater-air-pollution-nepal) — Technology, Environment and Society, chapter 5