Download Cl Need Jan 08 Meeting - Water Mission Country Programs Wiki

The Need for
Chlorine
Mission of
Water Missions

Provide Access to Safe Water and the opportunity to hear the Living
Water message

1.2 Billion people lack access to safe water


Each year:


1.7 – 2.2 million persons die from waterborne diseases
Each day:


WHO defines reasonable access as “availability of 20 liters per person
per day within 1 kilometer of user’s dwelling.”
5,000 children die from infectious diarrhea acquired from unsafe
drinking water
Each year:

4 billion episodes of diarrhea are caused by unsafe water
Safe Water

WHO Guidelines for Drinking Water Quality, 3rd Edition, Section 1.1
 “Safe drinking-water, as defined by the Guidelines, does not represent any
significant risk to health over a lifetime of consumption, including different
sensitivities that may occur between life stages.”
 Recommend each country use of risk-benefit analysis to set limits

Types of Contaminants


Large suspended matter (eg. soil)
Dissolved contaminants




Fertilizers, pesticides
Industrial run-off
Microbial contamination
Most disease is caused by microbial contamination
(WHO Guidelines, 3rd Edition, Section 1.1)
“The great majority of evident water-related health problems are the result of
microbial (bacteriological, viral, protozoan or other biological) contamination.”
 “In general terms, the greatest microbial risks are associated with ingestion of
water that is contaminated with human or animal (including bird) faeces.”
 “The potential health consequences of microbial contamination are such that its
control must always be of paramount importance and must never be
compromised.”

Types of Microbial
Contamination

Protazoa

Bacteria

Viruses
Protazoa

Life Stages



Cysts




Cysts in water or
elsewhere in environment
Out of cysts (excyst) in
intestines
Highly resistant to chlorine
Large size (3 – 8 microns)
Can be removed by
filtration
Examples of diseases


Cyrtosporidium
Giardia
Giardia Cyst
Bacteria

Smaller size




0.5 – 1.0 micron
Effectively removed only
by very tight filters such as
membranes
Vibrio Cholerae Bacteria
Easily destroyed by
chlorine
Diseases



Cholera
Typhoid
Gastroenteritis (diarrhea)
Vibrio Vulnificus Bacterium
Viruses

Very Small




0.1 - .01 micron
Not removable by common
filtration
Many effectively
inactivated with chlorine
Diseases



Poliovirus
Polio
Hepatitis
Rotavirus (intestinal, a
leading cause of diarrhea)
Hepatitis B Virus
Protazoa Tolerance to Chlorine
Source: CDC Pathogen Clearance List
PATHOGEN
Health
Significance
Persistance in
Water Supplies
Resistance to
Chlorine
Relative
Infectivity
Concentration of
Chlorine (ppm)
Time of
Exposure (min)
% Inactivation
Entomoeba
Hystolitica
High
Moderate
High
Low
2.0
10
99%
Giardia
Lamblia
High
Moderate
High
Low
1.5
10
99.9%
Toxoplasm
a gondii
High
Moderate
High
Unknown
100
1440
-
Cryptosporidium
parvum
High
Long
High
Low
80
90
99%
Bacteria Tolerance to Chlorine
Source: CDC Pathogen Clearance List
PATHOGEN
Health
Significance
Persistance in
Water Supplies
Resistance to
Chlorine
Relative
Infectivity
Concentration of
Chlorine (ppm)
Time of
Exposure (min)
% Inactivation
Burkholderia
pseudomallei
Low
May Multiply
Low
Low
1.0
60
99%
Campylobacte
r jejuni
High
Moderate
Low
Moderate
0.1
5
99 – 99.9%
Escherichia
coli
High
Moderate
Low
Low
0.5
<0.5
99.999999
%
E. coli
(enterohemorr
hagic)
High
Moderate
Low
High
0.5
<0.5
99.98 –
99.999999
%
Salmonella
typhi
High
Moderate
Low
Low
0.05
20
99.2%
Shigella
dysenteriae.
High
Short
Low
Moderate
0.05
<1
99.9%
-
-
-
-
0.5
1
99%
Vibrio cholerae
(smooth strain)
High
Short
Low
Low
0.5
<1
100%
Vibrio cholerae
(rugose
strain)
High
Short
Low
Low
2.0
20
99.999%
Yersinia
enterocolitica
High
Long
Low
Low
1.0
>30
82 – 92%
Shigella
sonnei
Virus Tolerance to Chlorine
Source: CDC Pathogen Clearance List
PATHOGEN
Health
Significance
Persistance in
Water Supplies
Resistance to
Chlorine
Relative
Infectivity
Concentration of
Chlorine (ppm)
Time of
Exposure (min)
% Inactivation
Coxsakie A
High
Long
Moderate
High
0.46 – 0.49
0.3
99%
Coxsackie
B
High
Long
Moderate
High
0.48 - 0.50
4.5
99%
Echovirus
High
Long
Moderate
High
0.48 – 0.52
1.8
99%
Hepatitis A
High
Long
Moderate
High
0.41
<1
99.99%
Polio Virus
High
Long
Moderate
High
0.5
12.72
99.99%
Adenovirus
High
Long
Moderate
High
0.17
4.41
99.99%
Noroviruse
s
High
Long
Moderate
High
1.0
0.07
99.99%
Rotavirus
High
Long
Moderate
High
0.20
0.25
99.99%
What Does Chlorine Do?
Chlorine

Will inactivate microbes if sufficient quantity and
time
 Time
 Often <1 minute, but some organisms more resistant
 30 minutes is WMI goal
 Quantity
 0.2 – 0.5 ppm is common amount in developed countries
 Need residual appropriate for distribution system



Consider tanks, household containers
We want to have safe water as the water is delivered to the
person’s mouth
Sample water and test and “end” of distribution system to
determine amount needed at LWTS or chlorinator
Living Water
Treatment System

Combines both filtration and chlorination

Effectively treats water that is contaminated by
major classes of microbial contaminants

Similar to the water treatment used by most
public water treatment facilities in developed
countries.

Both filtration and chlorination are necessary to
provide safe water
What to do if beneficiaries
object to chlorine taste

Do not eliminate chlorine!

Start at lower concentration and increase if
necessary
 0.2

– 0.5 ppm initially
If we are not chlorinating water
 We
are not providing safe water
 We are not meeting the mission of Water Missions