---
title: "Pathogenic pollution in drinking water"
subject: "Technology, Environment and Society"
chapter: 5
key: "semester_7/technology_environment_and_society:pathogenic-pollution-drinking-water"
source: https://www.bctengineer.com/q/semester_7/technology_environment_and_society/pathogenic-pollution-drinking-water
site: BCT Engineering
---

# Pathogenic pollution in drinking water

Technology, Environment and Society · Chapter 5: Water and Air Pollution

- Asked in: 2070 Asar, 8 marks
- Video: [Waterborne diseases | Waterborne Pathogens | Public Health and Water Safety | Prevention & Control](https://www.youtube.com/watch?v=GlTdIRxpxAQ) — tiny Predators
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/technology_environment_and_society/pathogenic-pollution-drinking-water
- Whole chapter: https://www.bctengineer.com/md/semester_7/technology_environment_and_society/chapter-5

## Question

What do you mean by pathogenic pollution in drinking water? Also write down its transmission route and prevention measures.

## Short answer

Pathogenic pollution is faecal contamination of water by pathogens causing choliera, typhoid, and diarrhoea. Transmission follows the faecal-oral route via water, hands, flies, soil, and food. Prevention includes toilets, source protection, chlorination, household boiling/filters, handwashing with soap, and health education.

## Answer

**Pathogenic pollution** of drinking water is the contamination of water by **disease-causing micro-organisms (pathogens)** – bacteria, viruses, protozoa and helminth (worm) eggs – that come mainly from human and animal faeces. It is the most dangerous form of water pollution in developing countries because even a small dose can cause disease and outbreaks.

#### Main pathogens and diseases
| Group | Pathogen | Disease |
|---|---|---|
| Bacteria | *Vibrio cholerae* | Cholera |
| Bacteria | *Salmonella typhi* | Typhoid |
| Bacteria | *Shigella*, *E. coli* | Dysentery, diarrhoea |
| Virus | Hepatitis A and E virus | Jaundice (hepatitis) |
| Virus | Rotavirus, poliovirus | Diarrhoea, polio |
| Protozoa | *Entamoeba*, *Giardia* | Amoebiasis, giardiasis |
| Helminth | Roundworm, hookworm | Worm infections |

**Indicator organism:** since pathogens are hard to test, water is tested for **faecal coliform / E. coli**. Nepal's National Drinking Water Quality Standards require **0 E. coli per 100 mL**.

**Sources:** open defecation near sources, leaking septic tanks and sewers, cross-connection of sewer and water pipes, uncovered wells and springs, animal waste, unsafe storage at home, flood water.

#### Transmission route (fecal-oral route)
```text
             +--> Fluids (water) ------+
             +--> Fingers -------------+
 FAECES -----+--> Flies ---------------+--> FOOD --> MOUTH
             +--> Fields/soil ---------+       (new host)
```

1. **Fluids** – drinking contaminated water directly (water-borne).
2. **Fingers** – unwashed hands touch food or mouth (water-washed diseases, due to lack of water for hygiene).
3. **Flies** – carry faecal matter to food.
4. **Fields** – contaminated soil and vegetables.
5. **Food** – prepared with contaminated water or hands.

#### Prevention measures
**At source and in the system**
1. Safe excreta disposal – toilets for all, no open defecation; latrines at least about 15 m from and downhill of water sources.
2. Protect intakes, springs and wells (fencing, sealed covers, sanitary seal).
3. Treatment: sedimentation, filtration (slow sand filter) and **disinfection by chlorination** with residual chlorine in the supply.
4. Maintain pipelines; avoid intermittent supply and cross-connection with sewers.
5. Regular water quality testing for E. coli.

**At household level**
6. Boiling, ceramic or biosand filters, chlorination (e.g. Piyush), **SODIS** (solar disinfection).
7. Safe storage in covered, narrow-mouthed vessels; use a ladle, not hands.

**Hygiene and health**
8. Hand washing with soap at critical times.
9. Food hygiene and fly control.
10. Health education, vaccination (typhoid, polio, rotavirus, hepatitis A) and ORS/zinc for diarrhoea.

## Check yourself

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

1. Pathogenic pollution of drinking water means:
   A. Contamination by heavy metals only
   B. Contamination by disease-causing micro-organisms mainly from faeces
   C. Excess fluoride in rocks
   D. Warm water from factories
   Answer: B. It is contamination by bacteria, viruses, protozoa and worm eggs, mainly from human and animal faeces. (Key point: Definition)

2. Which organism is tested as indicator of faecal contamination, and what is Nepal's standard?
   A. Salmonella; 10 per 100 mL
   B. Faecal coliform / E. coli; 0 per 100 mL
   C. Giardia; 5 per 100 mL
   D. Vibrio cholerae; 1 per 100 mL
   Answer: B. Pathogens are hard to test, so E. coli is used; the standard is 0 per 100 mL. (Key point: Indicator organism)

3. Which pairing is correct?
   A. Vibrio cholerae - typhoid
   B. Salmonella typhi - cholera
   C. Vibrio cholerae - cholera
   D. Giardia - polio
   Answer: C. Vibrio cholerae causes cholera; Salmonella typhi causes typhoid. (Key point: Pathogen-disease match)

4. Where should latrines be placed relative to water sources?
   A. At least about 15 m away and downhill of the source
   B. Immediately next to the well
   C. Uphill of the source
   D. Within 1 m
   Answer: A. Latrines should be about 15 m or more away and downhill so that leakage does not reach the source. (Key point: Latrine siting)

## Related in Technology, Environment and Society

- [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
- [Fecal-oral infection route and prevention](https://www.bctengineer.com/question.md?key=semester_7%2Ftechnology_environment_and_society%3Afecal-oral-route-prevention) — Technology, Environment and Society, chapter 5, asked 2×
- [Indoor air pollution in Nepal and counter measures](https://www.bctengineer.com/question.md?key=semester_7%2Ftechnology_environment_and_society%3Aindoor-air-pollution-nepal) — Technology, Environment and Society, chapter 5
- [Pollution, onsite sanitation, health education, fecal-oral](https://www.bctengineer.com/question.md?key=semester_7%2Ftechnology_environment_and_society%3Apollution-sanitation-fecal-oral) — Technology, Environment and Society, chapter 5
- [Fecal-oral route and health education](https://www.bctengineer.com/question.md?key=semester_7%2Ftechnology_environment_and_society%3Afecal-oral-health-education) — Technology, Environment and Society, chapter 5
- [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

## Related in other subjects

- [Fecal-oral route and preventive measures](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Afecal-oral-preventive) — Water Supply Engineering, chapter 4
- [Water quality parameters and Nepal drinking water standards](https://www.bctengineer.com/question.md?key=semester_7%2Fenvironment_and_pollution_control%3Anepal-drinking-water-quality-standards) — Environment and Pollution Control, chapter 4
- [Fecal-oral disease transmission route](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Afecal-oral-route) — Water Supply Engineering, chapter 4, asked 7×
- [Waterborne diseases, transmission, prevention](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Awater-borne-diseases) — Water Supply Engineering, chapter 4, asked 3×