---
title: "Total demand, village survey 2013, design 15 years"
subject: "Water Supply Engineering"
chapter: 3
key: "semester_5/water_supply_engineering:demand-c69"
source: https://www.bctengineer.com/q/semester_5/water_supply_engineering/demand-c69
site: BCT Engineering
---

# Total demand, village survey 2013, design 15 years

Water Supply Engineering · Chapter 3: Quantity of Water

- Asked in: 2069 Chaitra, 8 marks
- Video: [FORECAST THE POPULATION OF GIVEN YEAR- WATER SUPPLY ENG. 4TH SEMESTER @Er.dipesh186 NUMERICAL](https://www.youtube.com/watch?v=EsTkhEvqRDg) — Er. Dipesh Bhatt
- 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-c69
- Whole chapter: https://www.bctengineer.com/md/semester_5/water_supply_engineering/chapter-3

## Question

The survey data collected for a water supply scheme in a village of Nepal is given below:

Survey year = 2013; Base period = 3 years; Design period = 15 years; Population = 250; No. of cows = 200; No. of goats = 500; No. of chickens = 5000; Annual population growth rate = 1.5%; No. of day scholars in school = 100; No. of boarders in school = 10; No. of health post = 1; No. of tea shop = 1; VDC office = 1.

Calculate total water demand for design year.

## Short answer

Survey year 2013, design year 2031. Population forecasted 327 by geometric growth. Total water demand: 34.6 m3/day (0.40 l/s) after adding 15% losses.

## Answer

Survey year 2013; base period 3 years and design period 15 years: design year 2031, $n = 18$ years.

#### Design population
$$
P_{2031} = 250\times(1.015)^{18} = 327
$$

#### 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) | 327 | 45 l/c/d | 14,708 |
| Day scholars | 100 | 5 l/c/d | 500 |
| Boarders | 10 | 45 l/c/d | 450 |
| Cows | 200 | 45 l/d | 9,000 |
| Goats | 500 | 5 l/d | 2,500 |
| Chickens | 5,000 | 0.2 l/d | 1,000 |
| Health post | 1 | 1000 l/d | 1,000 |
| Tea shop | 1 | 500 l/d | 500 |
| VDC office (10 staff) | 10 | 45 l/staff | 450 |
| **Net demand** | | | **30,108** |

Losses and wastage $= 15\%$ of net demand $= 4{,}516$ l/day

$$
Q_{avg} = 30{,}108 + 4{,}516 = 34{,}624\ \text{l/day} = 34.62\ \mathrm{m^3/day} = 0.40\ \text{l/s}
$$

**Answer: Design population = 327; total water demand = 34.6 m$^3$/day (0.40 l/s).**

## Check yourself

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

1. Survey 2013, base period 3 and design period 15 years. n is
   A. 15 years
   B. 18 years
   C. 3 years
   D. 20 years
   Answer: B. Design year 2031, 18 years after the survey. (Key point: Value of n)

2. How are losses and wastage added?
   A. 15% of the net demand (30,108) is added to give 34,624 l/day
   B. 15% is subtracted
   C. 15% of the domestic demand only is added
   D. 50% of the net demand is added
   Answer: A. Losses are 15% of net demand: 4,516 l/day. (Key point: Losses)

## Close variants set in other exams

- [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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