---
title: "Design discharge 2030, Surkhet village"
subject: "Water Supply Engineering"
chapter: 3
key: "semester_5/water_supply_engineering:demand-c71"
source: https://www.bctengineer.com/q/semester_5/water_supply_engineering/demand-c71
site: BCT Engineering
---

# Design discharge 2030, Surkhet village

Water Supply Engineering · Chapter 3: Quantity of Water

- Asked in: 2071 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-c71
- Whole chapter: https://www.bctengineer.com/md/semester_5/water_supply_engineering/chapter-3

## Question

Calculate the design discharge for design year 2030 for a village in Surkhet District. The data collected in survey year 2015 is as below:

Survey year population = 1500; Population growth rate = 2.0% per year; Number of buffalos = 345; Number of cows = 450; Number of goats = 800; Number of chickens = 2000; Number of boarder students = 64; Number of day scholar students = 450; Number of offices = 3.

## Short answer

Design population 2019 after 15 years at 2%. Net demand 137501 l/d; adding 15% losses gives 158126 l/d = 158.13 m3/d = 1.83 l/s. Design discharge: max day 2.75 l/s, peak hour 5.49 l/s.

## Answer

Survey year 2015, design year 2030, so $n = 15$ years.

#### Design population
$$
P_{2030} = 1500\times(1.02)^{15} = 2{,}019
$$

#### 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.

| Demand | Quantity | Rate | Demand (l/day) |
|---|---|---|---|
| Domestic (45 lpcd) | 2,019 | 45 l/c/d | 90,846 |
| Boarders | 64 | 45 l/c/d | 2,880 |
| Day scholars | 450 | 5 l/c/d | 2,250 |
| Buffaloes + cows | 795 | 45 l/d | 35,775 |
| Goats | 800 | 5 l/d | 4,000 |
| Chickens | 2,000 | 0.2 l/d | 400 |
| Offices (10 staff each) | 30 | 45 l/staff | 1,350 |
| **Net demand** | | | **137,501** |

Losses and wastage $= 15\%$ of net demand $= 20{,}625$ l/day

$$
Q_{avg} = 137{,}501 + 20{,}625 = 158{,}126\ \text{l/day} = 158.13\ \mathrm{m^3/day} = 1.83\ \text{l/s}
$$

#### Design discharge
- Maximum day demand $= 1.5\times1.83 = 2.75$ l/s (source, intake and transmission main).
- Peak hour demand $= 3\times1.83 = 5.49$ l/s (distribution).

**Answer: Design discharge (maximum day) = 2.75 l/s; average demand = 1.83 l/s (158.1 m$^3$/day); peak hour = 5.49 l/s.**

## Check yourself

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

1. How are buffaloes and cows treated?
   A. As small animals at 5 l/d
   B. Buffaloes at 45 and cows at 5 l/d
   C. Ignored because livestock are not domestic
   D. As big animals together: 345 + 450 = 795 at 45 l/d
   Answer: D. Cows and buffaloes are big animals at 45 l/d each. (Key point: Animal grouping)

2. For source, intake and transmission main, which discharge governs?
   A. Maximum day demand = 1.5 x Q_avg = 2.75 l/s
   B. Average demand 1.83 l/s
   C. Peak hour demand 5.49 l/s
   D. Net demand without losses
   Answer: A. Supply components are designed for the maximum day demand. (Key point: Design discharge)

3. What is the peak hour demand used for?
   A. The source yield check
   B. The distribution system, taken as 3 x Q_avg = 5.49 l/s
   C. Storage tank volume only
   D. Sizing the intake weir
   Answer: B. Distribution pipes must carry the peak hourly flow, 3 x 1.83 l/s. (Key point: Peak hour use)

## Close variants set in other exams

- [Design discharge 2040, Ilam rural municipality](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Ademand-c76) — Water Supply Engineering, chapter 3, asked 2×

## Related in Water Supply Engineering

- [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×
- [Total demand, village survey 2013, design 15 years](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Ademand-c69) — Water Supply Engineering, chapter 3, asked 2×
- [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
- [Population 2088 by three methods, design year demand](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Apop-k72) — Water Supply Engineering, chapter 3

## Related in other subjects

- [5th year peak load with population growth](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Afifth-year-peak-load-population-growth) — Transmission and Distribution System Design, chapter 6, asked 7×
- [5th year peak load, incremental growth rate](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Afifth-year-peak-load-incremental-growth) — Transmission and Distribution System Design, chapter 6, asked 7×
- [Asphalt Institute design: 1500 pcu/day, 5% growth](https://www.bctengineer.com/question.md?key=semester_7%2Ftransportation_engineering_ii%3Aasphalt-institute-design-1500-pcu) — Transportation Engineering II, chapter 2
- [Design discharge from given data](https://www.bctengineer.com/question.md?key=semester_6%2Fsanitary_engineering%3Adesign-discharge-sewer-75000) — Sanitary Engineering, chapter 2