---
title: "Demand of rural area survey 2019, 1.77% growth"
subject: "Water Supply Engineering"
chapter: 3
key: "semester_5/water_supply_engineering:demand-b78"
source: https://www.bctengineer.com/q/semester_5/water_supply_engineering/demand-b78
site: BCT Engineering
---

# Demand of rural area survey 2019, 1.77% growth

Water Supply Engineering · Chapter 3: Quantity of Water

- Asked in: 2078 Bhadra, 8 marks
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/water_supply_engineering/demand-b78
- Whole chapter: https://www.bctengineer.com/md/semester_5/water_supply_engineering/chapter-3

## Question

A survey was carried out in 2019 in a rural area of Nepal and the following data were obtained: Population = 4460, Offices = 3 nos, Day students = 654, boarding students = 145, Cows and buffaloes = 480, goats and pigs = 855. A 15% of net water demand is considered as compensation for losses and wastage. Estimate the total water demand for the scheme if base period is 2 years and design period is 20 years. Consider the annual population growth rate as 1.77%.

## Short answer

Population grows geometrically at 1.77% for 22 years to 6,561. Applying rural unit demands and 15% losses gives total water demand 382 m3/day, about 4.42 l/s.

## Answer

Survey year 2019; base period 2 years and design period 20 years, so the design year is 2041, i.e. $n = 22$ years after the survey.

#### Design population
$$
P_{2041} = 4460\times(1.0177)^{22} = 6{,}561
$$

#### Water demand
**Design values assumed** (Nepal rural water supply practice): domestic 45 lpcd (public taps); day scholar 5 l/d; boarder 45 l/d; office staff 45 l/d with 10 staff per office; big animal (cow, buffalo) 45 l/d; small animal (goat, pig) 5 l/d; poultry 0.2 l/d; health post 1000 l/d; tea shop 500 l/d; losses and wastage 15% of net demand; maximum day factor 1.5 and peak hour factor 3. Losses and wastage are 15% of net demand as given. Student and livestock numbers are taken as constant.

| Demand | Quantity | Rate | Demand (l/day) |
|---|---|---|---|
| Domestic (45 lpcd) | 6,561 | 45 l/c/d | 295,245 |
| Day students | 654 | 5 l/c/d | 3,270 |
| Boarding students | 145 | 45 l/c/d | 6,525 |
| Offices (10 staff each) | 30 | 45 l/staff | 1,350 |
| Cows + buffaloes | 480 | 45 l/d | 21,600 |
| Goats + pigs | 855 | 5 l/d | 4,275 |
| **Net demand** | | | **332,265** |

Losses and wastage $= 15\%$ of net demand $= 49{,}840$ l/day

$$
Q_{avg} = 332{,}265 + 49{,}840 = 382{,}105\ \text{l/day} = 382.10\ \mathrm{m^3/day} = 4.42\ \text{l/s}
$$

**Answer: Design population = 6,561; total water demand = 382 m$^3$/day (4.42 l/s).**

## Check yourself

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

1. Survey 2019, base 2, design 20 years: n for growth?
   A. 20
   B. 22
   C. 18
   D. 2
   Answer: B. Design year 2041, so 22 years after the survey. (Key point: Years of growth)

2. What is the design population?
   A. 4,460
   B. 5,000
   C. 6,561
   D. 9,000
   Answer: C. 4460 x 1.0177^22 = 6,561. (Key point: Population)

3. How is office demand computed?
   A. 3 offices x 1,000 l
   B. 30 staff (10 per office) x 45 l = 1,350 l/d
   C. 3 x 45 l
   D. Neglected
   Answer: B. 10 staff per office x 3 = 30 staff at 45 l/d. (Key point: Office demand)

4. Net 332,265 l/d with 15% losses gives:
   A. 382,105 l/d
   B. 332,265
   C. 498,000
   D. 347,000
   Answer: A. 332,265 + 49,840 = 382,105 l/d = 382 m3/day. (Key point: Final demand)

## Related in Water Supply Engineering

- [Rural village demand, survey 2070 BS, base year 2073](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Ademand-as70) — Water Supply Engineering, chapter 3
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- [Demand of rural municipality, base period 3 years](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Ademand-bk79) — Water Supply Engineering, chapter 3
- [Demand of rural municipality 2018, 15,000 pop](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Ademand-c74) — Water Supply Engineering, chapter 3
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- [Average demand, village survey 2013, design 25 years](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Ademand-c73) — Water Supply Engineering, chapter 3, asked 2×

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