Drinking Water Quality- Environmental Engineering 1

Drinking water

1. CVNG2012
ENVIRONMENTAL ENGINEERING 1
Lecturer: Vincent Cooper
PHYSICAL
CHEMICAL
MICROBIOLOGICAL
DRINKING WATER QUALITY

2. Water Quality
•Provision of safe, palatable, and ample public water supplies
•Proper disposal of or recycling of wastewater and solid wastes
•Control of water, soil, and atmospheric pollution (including noise as
an atmospheric pollution)

3. Potable Water
•Crystal Clear
•Colourless
•Pathogen-free
•Cool
3

4. WASA
Guide
lines
Drinking Water Standards
4

5. Drinking
Water
Standards

6. Sources of Water
Surface water
•Rivers and
streams
6

7. Surface water
•Lakes
•Reservoirs
Sources of
Water
7

8. Sources of Water
Groundwater
•Springs
•Wells
8

9. Sources of Water
Seawater
9

10. Sources of Water
New water
10

11. Water Quality
Three main categories to describe drinking water quality
•Physical—associated with appearance of water
•Colour
•Turbidity
•Taste and odour
•Temperature
•Chemical
•Evidenced by their observed reactions, such as comparative performance of hard and
soft water in laundering
•Differences may not be visible
•Microbiological
•Important for public health

12. Physical Properties

13. Physical Characteristics
Turbidity
Presence of suspended material such as clay, silt, finely divided organic
material and other particulate material in water.
•Unit of measurement: Turbidity Unity (TU); NephlometricTurbidity
Unit (NTU)
•May not adversely affect health
•Water containing such particles may require treatment for intended
use

14. Visual of turbidity

15. Other Physical Characteristics
Colour
•caused by dissolved organic material
•Not usually objectionable (health-wise)
•Aesthetically objectionable
Taste and Odour
•May be caused by foreign matter such as organic compounds,
inorganic salts, dissolved gases
•Sources could be from agriculture, domestic, natural
•Should be free from objectionable3 taste or odour at point of use

16. Chemical Properties

17. Microbiological Properties

18. Removal of Pathogens in Drinking Water
Prepared by Dr. Susan J. Masten, Department of Civil and Environmental Engineering, Michigan State University

19. Microbiological
Quality
Pathogens in Water
Peavy and Rowe, 1985

20. Microbiological Quality
Pathogen Indicators
•Can’t analyze for all known pathogens
–Time consuming
–Expensive
•Tests for specific pathogens only when there is reason to suspect their
presence
•Instead water purity checked using indicator organisms

21. Pathogen Indicators
Indicator Organism
One whose presence presumes that
contamination has occurred and
suggests the nature and extent of
contamination

22. Pathogen Indicators
Characteristics
1.Be applicable to all types of waters
2.Always be present when pathogens are present
3.Always be absentwhen pathogens are absent
4.Lend itself to routine quantitative testing
procedures without interference from or
confusion of results because of extraneous
organisms
5.Not be pathogenic itself

23. Pathogen Indicators
Most waterborne pathogens from faecal contamination of water
Any organism native to intestinal tract and meeting above
criteria will be suitable
Faecal coliform group suitable
Composed of several strains, mainly Escherichia coli (E.Coli)
•Found exclusively in the intestinal tract of warm‐blooded animals
•Also, excreted in large numbers with excreta
•Non‐pathogenic
•Have longer survival time outside the animal body than most
pathogens
•Note other coliform groups that flourish outside intestinal tract
•Native to soil and decaying vegetation
•This coliform group also included because the life cycle of some pathogens
may included periods in the soil

24. Pathogen Indicators
For drinking water
Total coliform group
• Faecal
• Non‐faecal
For wastewater
Faecal coliform
Testing procedure relatively simple
•Membrane filtration technique
•Units: CFU/100 mL

25. E.Colias faecalcontamination indicator
C.thermo
Bacteria
Animal intestinal
bacteria
Free living
bacteria
C. thermo
Human intestinal
bacteria
E. Coli
Pathogenic
TC

26. Things you know now
1.What are the pathogens that cause major water-related outbreaks
2.What is an indicator organism
3.What are the characteristics of an indicator organism
4.Why are total and faecal coliform tested in water treatment