---
title: "Wholesome water and its requirements"
subject: "Water Supply Engineering"
chapter: 1
key: "semester_5/water_supply_engineering:wholesome-water-requirements"
source: https://www.bctengineer.com/q/semester_5/water_supply_engineering/wholesome-water-requirements
site: BCT Engineering
---

# Wholesome water and its requirements

Water Supply Engineering · Chapter 1: Introduction

- Asked in: 2081 Bhadra, 1+3 marks; 2066 Bhadra (old course) (asked 2 times)
- Video: [SAFE AND WHOLESOME WATER](https://www.youtube.com/watch?v=vQI6cOX9-Lo) — MGUMST JAIPUR
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/water_supply_engineering/wholesome-water-requirements
- Whole chapter: https://www.bctengineer.com/md/semester_5/water_supply_engineering/chapter-1

## Question

What is meant by wholesome water? List the requirements for wholesome water according to its physical, biological and chemical characteristics.

## Short answer

Wholesome water is safe, clear, odourless, pleasant taste, free from harmful organisms and chemicals. Physical: turbidity ≤5 NTU, colourless, odourless, cool. Biological: zero E. coli/100ml. Chemical: pH 6.5-8.5, TDS ≤1000 mg/l, hardness ≤500 mg/l, iron ≤0.3 mg/l, arsenic ≤0.05, fluoride ≤1.5, nitrate ≤50 mg/l, residual chlorine 0.1-0.2 mg/l.

## Answer

**Wholesome water** is water that is safe to drink and suitable for domestic use. It is free from harmful organisms and chemicals, is clear, colourless, odourless, pleasant to taste, and does not harm health.

#### Requirements
**Physical characteristics**
- Turbidity low (Nepal standard: 5 NTU, up to 10 NTU in small supplies).
- Colourless (colour less than 5 TCU, maximum 15) and odourless.
- Pleasant taste; temperature cool (about 10 to 25 degrees C).

**Biological (bacteriological) characteristics**
- Free from pathogenic bacteria, viruses, protozoa and helminths.
- Zero E. coli / thermotolerant coliform per 100 ml at the consumer's tap.
- Free from algae and other organisms that cause taste, odour or toxins.

**Chemical characteristics**
- pH in range 6.5 to 8.5.
- Total dissolved solids not above 1000 mg/l; hardness not above 500 mg/l as CaCO3.
- Iron up to 0.3 mg/l, manganese up to 0.2 mg/l, chloride up to 250 mg/l, sulphate up to 250 mg/l.
- Toxic substances within limits: arsenic 0.05 mg/l, fluoride 0.5 to 1.5 mg/l, nitrate 50 mg/l, lead 0.01 mg/l.
- Free residual chlorine about 0.1 to 0.2 mg/l at the tap.

(Values are as in the Nepal Drinking Water Quality Standards, 2062.)

## Check yourself

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

1. What is the required E. coli level at the consumer's tap?
   A. Zero per 100 ml
   B. 10 per 100 ml
   C. Up to 100 per 100 ml
   D. Not specified
   Answer: A. Zero E. coli or thermotolerant coliform per 100 ml is required. (Key point: Bacteriological limit)

2. The Nepal standard limit for arsenic is:
   A. 0.5 mg/l
   B. 0.01 mg/l
   C. 0.05 mg/l
   D. 5 mg/l
   Answer: C. Arsenic limit in the answer is 0.05 mg/l. (Key point: Arsenic limit)

3. Nepal standard turbidity for wholesome water is:
   A. 50 NTU
   B. 25 NTU
   C. 1000 NTU
   D. 5 NTU, up to 10 NTU in small supplies
   Answer: D. Turbidity should be low: 5 NTU, up to 10 NTU in small supplies. (Key point: Turbidity)

## Related in Water Supply Engineering

- [Objectives of supply; wholesome water requirements](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Aobjectives-requirements-wholesome) — Water Supply Engineering, chapter 1, asked 2×
- [Potable, wholesome, polluted, contaminated water](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Apotable-wholesome-polluted-contaminated) — Water Supply Engineering, chapter 1
- [Potable, wholesome water; function in body](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Adefine-potable-wholesome-function) — Water Supply Engineering, chapter 1
- [Pure/impure, potable/wholesome, polluted/contaminated](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Adifferentiate-water-types) — Water Supply Engineering, chapter 1

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