Quality of water source for supply

1. CEE 507: RURAL WATER
SUPPLY ENGINEERING-
[QUALITY OF WATER]
Eng. CHU DICKSON
M.Eng. In Environmental Engineering
Dip. Occupational Health & Safety
chnkoli@gmail.com
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2. Content
Introduction
Requirements of water for domestic use
Common impurities in water and their effects
Water analysis
Standards for water quality

3. INTRODUCTION
 Before a source of water is relied on for town supply, there are two things that must
be considered; quality and quantity of the water source.
 The qualities of different waters varies greatly; that some are pleasant to the taste
and smell, and that others are not. What is more important, that some are perfectly
harmless, while others are liable to produce ill-health when habitually drunk, or
even to spread epidemic diseases.
 It is necessary therefore, that the engineer who is to propose a source of water for
supply, to have knowledge on the causes on the difference in the qualities of water,
although he need not have any deep knowledge of Chemistry

4. INTRODUCTION
 The primary objective of water treatment and purification is to collect water from
best available sources and subject it to processing which will ensure water of good
physical quality, free from unpleasant taste, or odor and containing nothing which
may be detrimental to health.
 It is not possible to find absolutely pure water in nature. Chemically pure water is
the one which contains two parts of hydrogen and one part of oxygen.

5. IMPORTANT REQUIREMENTS OF
WATER FOR DOMESTIC USE
 It should be colorless and sparkling
 It should be of good taste, free from odor
 It should be reasonably soft
 It should be plentiful and cheap
 It should be free from pathogens
 It should be free from objectional dissolved gasses such hydrogen sulphite
 It should be free from harmful salts
 It should be free from objectional minerals e.g. iron, manganese, lead etc
 It should be free from radio-active substances such as radium.
 It should not lead to scale formation, and should not be corrosive.

6. COMMON IMPURITIES IN WATER AND
THEIR EFFECTS
 Impurities in water are classified into three heads;
i. Suspended impurities
ii. Dissolved impurities
iii. Colloidal impurities
Suspended impurities are those which normally remain in suspension. They are
microscopic and make water turbid.
Dissolved impurities are not visible, but they are large since water is a good solvent. They
cause bad taste, hardness and alkalinity. Sometimes they are harmful.
Colloidal impurities are electrically charged. Due to this, the colloidal particles, usually
very small in size, remain in constant motion and do not settle.

7. WATER ANALYSIS
 Various types of impurities present in water can be determined by water analysis. This
analysis is done both for raw water as well as treated or purified water.
 The analysis of water may be divided into three classes;
i. Physical examination
ii. Chemical examination
iii. Microbiological examination
Sampling: The proper collection of water sample entails the most careful consideration of
all relevant circumstances, as regards choice of sampling point, method of collection and
frequency of testing.
The samples should be collected in clean and sterilized bottles having stoppers. The water
and the bottle should not be touched while collecting the sample.

8. WATER ANALYSIS
 Physical Examination: These consist of;
i. Color Test
ii. Taste and odor test
iii. Turbidity Test
iv. Temperature

9. WATER ANALYSIS
 Chemical Examination: Chemical
Test are carried out to determine the
following
i. Total solids
ii. Chlorides
iii. Hardness
iv. pH
v. Metals and other chemical
substances
vi. Nitrogen and its compounds
vii. Dissolved gasses

10. WATER ANALYSIS
 Biological Examination: These Test
consist of;
i. Total count or agar plate count
test
ii. Coliform Test
iii. Test for E-coli