---
title: "Short note: On site sanitation"
subject: "Technology, Environment and Society"
chapter: 5
key: "semester_7/technology_environment_and_society:onsite-sanitation-note"
source: https://www.bctengineer.com/q/semester_7/technology_environment_and_society/onsite-sanitation-note
site: BCT Engineering
---

# Short note: On site sanitation

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

- Asked in: 2079 Baisakh, 4 marks
- Video: [03 - Sanitation systems (explaining the Onsite and Conventional systems)](https://www.youtube.com/watch?v=dEPCQ025ZUQ) — Urban_ASCI
- 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/onsite-sanitation-note
- Whole chapter: https://www.bctengineer.com/md/semester_7/technology_environment_and_society/chapter-5

## Question

Write a short note on on-site sanitation.

## Short answer

On-site sanitation treats human waste where it is produced, without sewers. Common types include pit latrine, VIP, pour-flush, septic tank and ecosan; it is low-cost, needs little water, suitable for rural areas, but risks groundwater contamination and requires safe pit emptying.

## Answer

**On-site sanitation** is a sanitation system in which human excreta (and sometimes waste water) are collected, stored and treated at or near the place where they are produced, without the use of a sewer network. It is the most common system in rural and peri-urban Nepal because it is cheap and needs little water.

#### Common types
1. **Simple pit latrine** – a pit covered with a squatting slab; cheapest.
2. **VIP (Ventilated Improved Pit) latrine** – a vent pipe with fly screen removes smell and traps flies.
3. **Pour-flush latrine** – a water-seal pan flushed with 1–3 litres of water into one or two offset pits (twin pit allows alternate use and safe emptying).
4. **Septic tank with soak pit** – used in towns; sludge settles, effluent goes to a soak pit; needs periodic de-sludging.
5. **Ecosan / composting toilet** – separates urine and faeces; produces manure.

#### Advantages
- Low construction and running cost; can be built by households.
- Needs little or no water.
- Suitable for scattered settlements where sewers are not practical.

#### Disadvantages
- Risk of **groundwater contamination** if the pit is near a well (keep about 15 m or more away and downhill) or the water table is high.
- Needs safe pit emptying and faecal sludge management.
- Not suitable in very dense areas or rocky ground.

On-site sanitation, together with hand washing and safe water, breaks the fecal-oral route and was the basis of Nepal's ODF campaign.

## Check yourself

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

1. Why is on-site sanitation the most common system in rural and peri-urban Nepal?
   A. It requires a large public sewer investment
   B. It needs a large amount of water
   C. It is cheap and needs little water
   D. It needs skilled plant operators
   Answer: C. It is low in cost, can be built by households and needs little water, suiting scattered settlements without sewers. (Key point: Why on-site is common in Nepal)

2. Which description of latrine types is correct?
   A. VIP latrine uses a vent pipe with fly screen to remove smell and trap flies
   B. Pour-flush latrines use no water at all
   C. Septic tanks never need de-sludging
   D. Simple pit latrine is the most expensive type
   Answer: A. VIP has a vent pipe with fly screen; pour-flush uses 1-3 L water; septic tanks need periodic de-sludging; simple pits are cheapest. (Key point: Features of latrine types)

3. What is the main disadvantage and precaution noted for pit latrines?
   A. They cannot be emptied, so keep them uphill from wells
   B. They contaminate groundwater if near a well or the water table is high, so keep about 15 m or more away and downhill
   C. They produce electricity, so keep them near wells
   D. They only fail in rainy weather, so no distance is required
   Answer: B. Poor siting risks groundwater contamination; keep pits about 15 m or more from wells and downhill. (Key point: Groundwater risk)

## Related in Technology, Environment and Society

- [On-site sanitation and health education in Nepal](https://www.bctengineer.com/question.md?key=semester_7%2Ftechnology_environment_and_society%3Aonsite-sanitation-health-education) — Technology, Environment and Society, chapter 5
- [On-site vs off-site sanitation and fecal-oral route](https://www.bctengineer.com/question.md?key=semester_7%2Ftechnology_environment_and_society%3Aonsite-offsite-fecal-oral) — Technology, Environment and Society, chapter 5