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 WHO defines reasonable access as “availability of 20 liters per person per day within 1 kilometer of user’s dwelling.” Each year: 1.7 – 2.2 million persons die from waterborne diseases Each day: 5,000 children die from infectious diarrhea acquired from unsafe drinking water 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 Examples of diseases Cysts in water or elsewhere in environment Out of cysts (excyst) in intestines Cysts Highly resistant to chlorine Large size (3 – 8 microns) Can be removed by filtration Examples of diseases Cyrtosporidium Giardia Giardia Cyst

Bacteria Smaller size Easily destroyed by chlorine Diseases 0.5 – 1.0 micron Effectively removed only by very tight filters such as membranes Easily destroyed by chlorine Diseases Cholera Typhoid Gastroenteritis (diarrhea) Vibrio Cholerae Bacteria Vibrio Vulnificus Bacterium

Viruses Very Small Many effectively inactivated with chlorine Diseases 0.1 - .01 micron Not removable by common filtration Many effectively inactivated with chlorine Diseases Polio Hepatitis Rotavirus (intestinal, a leading cause of diarrhea) Poliovirus 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 Low 2.0 10 99% Giardia Lamblia 1.5 99.9% Toxoplasma gondii Unknown 100 1440 - Cryptospo-ridium parvum Long 80 90

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 1.0 60 99% Campylobacter jejuni High Moderate 0.1 5 99 – 99.9% Escherichia coli 0.5 <0.5 99.999999% E. coli (enterohemorrhagic) 99.98 – 99.999999% Salmonella typhi 0.05 20 99.2% Shigella dysenteriae. Short <1 99.9% Shigella sonnei - 1 Vibrio cholerae (smooth strain) 100% (rugose strain) 2.0 99.999% Yersinia enterocolitica Long >30 82 – 92%

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 0.46 – 0.49 0.3 99% Coxsackie B 0.48 - 0.50 4.5 Echovirus 0.48 – 0.52 1.8 Hepatitis A 0.41 <1 99.99% Polio Virus 0.5 12.72 Adenovirus 0.17 4.41 Noroviruses 1.0 0.07 Rotavirus 0.20 0.25

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