---
title: "Design discharge 2040, Ilam rural municipality"
subject: "Water Supply Engineering"
chapter: 3
key: "semester_5/water_supply_engineering:demand-c76"
source: https://www.bctengineer.com/q/semester_5/water_supply_engineering/demand-c76
site: BCT Engineering
---

# Design discharge 2040, Ilam rural municipality

Water Supply Engineering · Chapter 3: Quantity of Water

- Asked in: 2076 Chaitra, 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-c76
- Whole chapter: https://www.bctengineer.com/md/semester_5/water_supply_engineering/chapter-3

## Question

Calculate the design discharge for design year 2040 for a Rural Municipality in Ilam District. The data collected in survey year 2020 is as below:

Survey year population = 1600; Population growth rate = 2.3% per year; number of buffalos = 350; Number of cows = 500; Number of goats = 900; Number of chickens = 2500; Number of boarder students = 100; Number of day scholar students = 550; Number of offices = 5; Health post = 2 nos.

## Short answer

Design population in 2040 is 2,521 by geometric growth. Average demand is 193.4 m3/day or 2.24 l/s; maximum day demand is 3.36 l/s and peak hour demand is 6.72 l/s.

## Answer

Survey year 2020, design year 2040, so $n = 20$ years.

#### Design population
$$
P_{2040} = 1600\times(1.023)^{20} = 2{,}521
$$

#### 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. Fire demand is neglected for a rural area.

| Demand | Quantity | Rate | Demand (l/day) |
|---|---|---|---|
| Domestic (45 lpcd) | 2,521 | 45 l/c/d | 113,461 |
| Boarders | 100 | 45 l/c/d | 4,500 |
| Day scholars | 550 | 5 l/c/d | 2,750 |
| Buffaloes + cows | 850 | 45 l/d | 38,250 |
| Goats | 900 | 5 l/d | 4,500 |
| Chickens | 2,500 | 0.2 l/d | 500 |
| Offices (10 staff each) | 50 | 45 l/staff | 2,250 |
| Health posts | 2 | 1000 l/d | 2,000 |
| **Net demand** | | | **168,211** |

Losses and wastage $= 15\%$ of net demand $= 25{,}232$ l/day

$$
Q_{avg} = 168{,}211 + 25{,}232 = 193{,}442\ \text{l/day} = 193.44\ \mathrm{m^3/day} = 2.24\ \text{l/s}
$$

#### Design discharge
- Maximum day demand $= 1.5\times193{,}442 = 290{,}163$ l/day $= 3.36$ l/s (for source, intake and transmission main).
- Peak hour demand $= 3\times2.24 = 6.72$ l/s (for the distribution system).

**Answer: Design discharge (maximum day) = 3.36 l/s; average demand = 2.24 l/s (193.4 m$^3$/day); peak hour = 6.72 l/s.**

## Check yourself

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

1. Survey 2020 and design 2040: n?
   A. 40
   B. 10
   C. 20
   D. 2
   Answer: C. 2040 - 2020 = 20 years. (Key point: Years)

2. Design population at 2.3% growth?
   A. 1,600
   B. 2,521
   C. 3,000
   D. 2,000
   Answer: B. 1600 x 1.023^20 = 2,521. (Key point: Population)

3. Which flow is used for source, intake and transmission main?
   A. Average demand 2.24 l/s
   B. Peak hour 6.72 l/s
   C. Maximum day 3.36 l/s
   D. Fire demand
   Answer: C. Source and transmission main are designed for maximum day demand. (Key point: Design discharge)

## Close variants set in other exams

- [Design discharge 2030, Surkhet village](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Ademand-c71) — Water Supply Engineering, chapter 3, asked 2×

## 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
- [Population in survey year from design demand 800 m3](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Apop-s73) — Water Supply Engineering, chapter 3, asked 2×
- [Demand of rural area survey 2019, 1.77% growth](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Ademand-b78) — 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
- [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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