Water Sources and Water Treatment
• Drinking water should be essentially free of disease-causing microbes, but often this is not the case.
– A large proportion of the world’s population drinks microbially contaminated water, especially in developing countries
• Using the best possible source of water for potable water supply and protecting it from microbial and chemical contamination is the goal
– In many places an adequate supply of pristine water or water that can be protected from contamination is not available
• The burden of providing microbially safe drinking water supplies from contaminated natural waters rests upon water treatment processes
– The efficiency of removal or inactivation of enteric microbes and other pathogenic microbes in specific water treatment processes has been determined for some microbes but not others.
– The ability of water treatment processes and systems to reduce waterborne disease has been determined in epidemiological studies

• Integral to the preventive management of drinking-water quality.
• Preventing microbial and chemical contamination of source water is the first barrier against drinking-water contamination of public healthconcern.
• Water resource management and potentially polluting human activity in catchments and aquifers influence water quality.
• This impacts treatment steps required to ensure safe water
• Preventive action may be preferableto upgrading treatment.

• Assess land use influence on water quality
• Not normally undertaken by health authorities or drinkingwater supply agencies alone
• Establish close collaboration between public health authority, water supplier and resource management agency
– may include other sectors, .e.g., agriculture, traffic, tourism or urban development.
• National authorities must interact with other sectors to formulate national policy for integrated water resource management
• Set up regional and local structures to implement policy
– National authorities need to guide regional and local authorities by providing tools

• land cover modification
• extraction activities
• construction/modification of waterways
• application of fertilizers, herbicides, pesticides and other chemicals
• livestock density and application of manure
• road construction, maintenance and use
• various forms of recreation
• urban or rural residential development
– Pay particular attention to excreta disposal, sanitation, landfill and waste disposal
• other potentially polluting human activities, such as industry, military sites,

• Water table or surficial aquifer
– First water encountered through the soil or subsurface
– Often subject to contamination from the land surface
• Confined aquifer
– Water found below a confining subsurface later of clay, rock or other impervious material
– Often protected from contamination lan surface
• Both may contain geological chemical contaminants
– Arsenic and fluoride are probably of most health risk
• Confined aquifer water is often better protected from surface contamination

• Lakes, ponds and other and “confined” bodies of water
• Rivers, streams, creeks and other flowing bodies of water
• All are subject to direct contamination from wastewater and excreta discharges
• All are subject to contamination from land runoff
• Surface water should be assumed to be contaminated unless proven otherwise by direct and indirect evidence from observations and analysis

• Rainwater as it falls from the sky is essentially free of pathogens and toxic chemicals
• Airborne contaminants can cause low level contamination with microbes and chemicals
• Rainwater is collected primarily on roofs or other impervious collectors
– Contamination from roof/impervious surface chemicals and microbes is possible
• Rainwater is often stored in barrels, cisterns and other surface and subsurface collectors or impoundments
– Contamination is very likely unless special precautions are taken to protect the collected water from fecal and other sources of contamination

• Atmospheric water as clouds, fod and airborne mist can be harvested at it impacts impervious surfaces.
• Solar Stills
– Water evaporated from standing water also can be condensed and harvested
– Solar condensers collect evaporated water
– Solar energy can supply heat

• Water can be purified from sewage and other wastewater
• Reuse for non-potable purposes in encouraged
• Reuse for potable purposes is discouraged
– Indirect reuse is considered feasible and of less risk by recharging aquifers or reservoirs and allowing addition die-off and further treatment
• WHO and countries have regulations for nonpotable and potable reuse

Reservoirs, aquifers & other systems:
– store water
– protect it from contamination
• Factors influencing microbe reductions (site-specific)
– detention time
– temperature
– microbial activity
– water quality: particulates, dissolved solids, salinity
– sunlight
– sedimentation
– land use
– precipitation
– runoff or infiltration

– Above and below ground cisterns, reservoirs and tanks

• Material: Depends on Rx; easy to clean; lightweight, durable, impact- and oxidationresistant, heat-resistant (if thermal Rx)
– High-density polyethylene (HDPE) for chemical Rx
– Transparent beverage bottles for solar-UV + heat (PET)
– Black or opaque for solar-heat only
• Can adapt traditional vessels to safer storage
– Add cover
– Add spout or spigot

• Appropriate material, size, shape, dimensions,
– Depends on collection, Rx method, use conditions & user
• Volume: usually 10 and 30 liters (not too heavy)
– smaller volumes (1-1.5 L) for solar Rx; multiples
• Handles to facilitate lifting and carrying
• Stable base to prevent overturning
• Uniform size for standard chemical dosing
• Opening: large enough to fill and clean; small enough to discourage hands, cups or other dip utensils.
– Inlet: fitted with a lid
• Durable spigot or spout for pouring

Plastic vessels are commonly used – many have safe features
Properties
Composition
Volume (L)
Durability
Cleaning Ease
Lid
Faucet
CDC Vessel
Plastic
(HDPE)
20
Good
Yes
Yes
Yes
Jerry Can
Plastic
Varies
Acceptable Good
Yes, qualified
Yes
No
Oxfam
Plastic
14
Yes
Yes
Yes
Inside Cleaning Yes No, usually Yes
Chemical Dosing Ease Very easy Easy (may be variable) Very easy
Cost
Distribution Cost
Med.-High
High
Low
Low, if local
Med.-High
High
Traditional vessels, such as pots, urns and bowls can be made safe by covering and providing a dispenser
(spigot or spout)

• Inadequate storage results in microbial contamination and waterborne disease
• Improved storage vessels reduce microbial contamination and disease risks
• Improved storage can be coupled with household treatment to further improve microbial quality and reduce disease risks
• Best implemented and sustained if supported with behavior modification, education, motivation and social marketing

Increased Microbial Contamination (Decreased Microbial Quality) and
Infectious Disease Risks from Inadequately Stored Household Water
Location
Rural
Bangladesh
Calcutta,
India
Khartoum,
Sudan
Rural
Malawi
South
Sudan
Rangoon,
Burma
Storage
Vessel
Water jars
Widemouth vs.
narrownecked
Storage
Times
1-2 days
Not reported
Microbial
Quality
Impact?
Increased V. cholerae
Disease Impact?
Incr. (~10X higher) cholera rates
Not measured 4X higher cholera infections w/ wide-mouth
Reference
Spira et al.,
1980
Deb et al.,
1982
Clay jars
("zeers") in homes, etc.
Stored HH water; others
Not reported
Buckets
2 days to
1 month
Not reported
Not reported
Up to 2 days
Incr. Fecal indicators w/ time, summer, w/ dust events
Higher fecal coliforms
Increased fecal bacteria levels
Higher FC than source
Not Measured
Not measured
Not Measured
Not Measured
Hammad and Dirar,
1982
Lindskog and
Lindskog,
1988
Mascher et al., 1988
Han et al.,
1989

Increased Microbial Contamination (Decreased Microbial Quality) and
Infectious Disease Risks from Inadequately Stored Household Water
Location
Urban slum and rural villages,
Liberia
Kurunegala,
Sri Lanka
Large containers, open or closed
Earthen pots and others
Rural Africa Traditional
& metal jars
Rural
Malaysia
Various containers
Trujillo,
Peru
Storage
Vessel
Widemouth containers
Storage
Times
"A long time"
Not reported
24 hours or more
Not reported
Not reported
Microbial
Quality
Impact?
Higher enterobacters in stored than source water
Higher FC in stored unboiled water
Higher TC and
FC
Higher FC in unboiled than boiled water
Higher FC in stored than source waters
Disease Impact?
Reference
Not Measured
Not Measured
Not Measured
Higher diarrhea risks stored in wide-necked than narrow-necked
Increased cholera risks
Molbak et al., 1989
Mertens et al., 1990
Empereur et al., 1992
Knight et al.,
1992
Swerdlow et al., 1992

• Microbe levels reduced over time by natural antimicrobial processes and microbial death/die-off
• Human enteric viruses in surface water reduced 400-
1,000-fold when stored 6-7 months (The Netherlands)
– Indicator bacteria reductions were less extensive, probably due to recontamination by waterfowl.
• Protozoan cyst reductions (log
10
) by storage were 1.6 for Cryptosporidium and 1.9 for Giardia after about 5 months (The Netherlands; G.J Medema, Ph.D. diss.)
–
Recent ICR data indicates lower protozoan levels in reservoir or lake sources than in river sources; suggests declines in Giardia & Cryptosporidium by storage