The document discusses water-related diseases, highlighting their classification, causes, and effects on health, particularly in developing countries. It emphasizes the role of pathogens, contaminants, and environmental factors in waterborne diseases and outlines six major disease categories. The conclusion stresses the importance of controlling microbial quality and ensuring safe drinking-water supplies through comprehensive management strategies.

1. Water Supply and
Treatment Technology
(EHT 215)
LECTURER: SIR OAK

2. LECTURE 3
 Diseases associated with water
Learning objective:
After completing this topic, students should be able to:
• describe the classification of water-related disease.
• mention the waterborne pathogens and their significance in
water supplies.

3. Introduction
• Diseases related to water and sanitation are the major causes
of high morbidity and mortality in developing countries
especially in children and infants (under 5 years).
• Water may carry causative agents (pathogens) of
communicable diseases of man or provide the right
environment for the breeding and propagation of their vectors.
• The presence of contaminants in water can lead to adverse
health effects, including death, disability, illness or disorders.

4. Introduction cont…
• Contamination of drinking water supplies can occur in the
source water as well as in the distribution system after water
treatment has already occurred.
• The causes of water related disease include micro-organisms,
parasites, toxins and chemical contamination of water.
• Water-related disease refers to any significant adverse effects
on human health caused directly or indirectly by the condition,
or changes in the quantity or quality, of any waters.

5. Classification of Water-Related Disease
• There are three essential components for the classification:
the pathogens/agent responsible;
the type of water exposure;
the level of probability of a water cause; and
the host factor.
• In public health terms, include:
water treatment or sanitation measures required to remove
the disease-causing factors.

7. Categories of Water-related Disease
• Water-related diseases can be classified into 6 major categories, as
follows:
 waterborne microbiological disease
 waterborne chemical disease
 water hygiene disease
 water contact disease
 water vector habitat disease
water aerosol disease

10. Waterborne pathogens cont…
• In general, the probability of waterborne pathogens to cause
disease in man depends on:
How virulent they are
How they are ingested into the host
How high their concentration is
How resistant the host is

11. r = N V
R
Where r = factor related
V = variance of organism
N = number of organism
R = host resistant
when r > 1 then the disease may occur
When r < 1 then the diseases may probably will not occur.
Waterborne pathogens cont…

12. Factors that contribute to
prevalence of water related disease
• Insufficient water supplies and sanitation
• Inadequate housing and lack of hygienic conditions
• Lack of good health care
• Poor water resource management schemes

13. In conclusion
• The vast majority of health-related water quality problems is
caused by the presence of pathogens.
• Control of microbial quality is essential, and must never be
compromised.
• Nevertheless, it should be recognized that serious health
outcomes are still being caused by chemical contaminants.
• Securing safety of drinking-water supplies is based on the use
of multiple barriers, operating from the water resources in the
catchment area to the consumer.

14. Thank you