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Introduction

• "Water is life" is an old saying
• “Water is guilty unless proved innocent”
• The quality and quantity of water available to a community reflects its socio-economic status
• In developing countries, 80% of illnesses are water-associated, per WHO survey
• Unsafe water leads to diarrheal diseases in children, increasing infant and child mortality
• Effective, safe water supply programs need integrated efforts from various sectors, including the community
• Water problems in Ethiopia stem from poor maintenance, lack of community involvement, and spare parts shortages
• In 1992 E.C., safe water coverage in Ethiopia was 83.5% in urban and 24.7% in rural areas
• Essential drinking-water parameters: quality, quantity, accessibility, affordability, and continuity

Occurrence and Source of Water

• Water exists globally, but distribution, quality, amount, and presence vary by location
• Over 72% of the Earth's surface is water
• Oceans hold 97.2% of the earth's surface water, but that water is too salty for human consumption,
• 2% of the world's fresh water is frozen in glaciers and icecaps
• Only about 0.8% of the total water is usable and also not evenly distributed or properly used

Improved and Unimproved Drinking-Water Sources:

• Improved drinking-water sources include:
  • Piped water into dwelling, public tap or standpipe, tubewell or borehole, protected dug well or spring, and rainwater collection
• Unimproved drinking-water sources include:
  • Unprotected dug well or spring, cart with small tank/drum, tanker truck provision, surface water
  • Surface water includes rivers, dams, lakes, ponds, streams, canal, and irrigation channel
  • Bottled water is also considered an unimproved drinking-water source

Ground Water

• The total precipitation that percolated downward into the porous space in the soil and rock
• Groundwater is the most practical and naturally safe water source
• Groundwater examples include springs and wells

Advantages of Groundwater

• Comparatively free from disease-causing microorganisms
• Usable without further treatment if protected and treated after construction
• Naturally stored underground, remains protected and available

Disadvantages of Groundwater

• Requires pumping to access, unless from a spring
• May contain excess dissolved mineral amounts
• Can be poor in oxygen content

Surface Water and Rainwater

• Surface water includes rivers, streams, lakes, ponds, etc
• Surface water is not uniformly distributed across the Earth's surface
• Rainwater is an effective water source in regions with frequent rainfall
• Rainwater is a reliable and inexpensive water supply for smaller communities and families

Advantages of Rainwater

• A reliable water source, regardless of rain frequency
• An inexpensive and safe supply option that may not need pumps or pipes
• Cisterns prevent disease spread
• Can reduce burden on Ethiopian and African women and children involved in water collection
• Can be used in semi-arid and arid areas
• Rainwater is the purest source

Ocean Water

• Ocean water cannot be consumed directly
• It must undergo desalination which is the removal of salt

Public Health Importance of Water

• Physiological needs: The body is 70% water; 2.0-2.5 liters daily is needed
  • Milk is about 90% water, while fish is about 80%
• Balance: 2-2.5L intake (1.5L drink, 0.6-1.0L food, 0.3-0.4L oxidation) balances loss (1.5L urine, 0.4-0.6L sweat, 0.35-0.4L breathing, 0.1-0.14L feces).
• Domestic purposes: Cleaning, washing, swimming, watering livestock
• Recreational: Swimming, boating, fishing, skiing
  • Examples include Lakes Langano and Ziqay
• Other applications: agriculture, transportation, power, industry
• Significant global and national problem: lack of safe, adequate water
  • Globally: 23% urban and 64% rural people in developing countries lack safe drinking water
  • 80% of diseases in developing countries are due to unsafe water, with resulting morbidity from dysentery, typhoid, diarrhea, helminthiasis, and skin/eye infections.
• Ethiopia's status: Only 26% have safe water (83% urban and 20% rural); less than 10 liters/capita/day (HSDP).

Impurities of Water

• Impurities include dissolved gases, microorganisms chemicals, minerals and suspended matter
• Divided into;
  • Suspended Impurities (microorganisms, suspended solids, algae)
  • Dissolved Impurities (gases, minerals, toxic salts)

Water and Disease

• 30,000 people each day die from water-associated diseases, based on a WHO survey
• 80% of all illnesses in developing countries are water-related
• Types of water pollution: biological and chemical

Water-Associated Diseases

• Diseases caused by inadequate water supply and sanitation, divided into four categories:
  • Water-borne
  • Water-washed
  • Water-based
  • Water-related

Water Borne Diseases

• The enteric or intestinal infections caused by bacteria that are transmitted through water contamination by fecal matter which is a passive vehicle for the infectious agent
• Diseases:
  • Bacteria: typhoid and paratyphoid fever, cholera, diarrheas
  • Virus: Hepatitis A, Poliomyelitis, Viral gastroenteritis
  • Protozoa: Amoebic dysentery, Giardia (lambliasis), Balantidiasis
  • Helminthes: Helminthiasis caused by Ascaris and teaneas.
• Prevention: water treatment

Water-Washed and Water-Based Diseases

• Water-washed diseases are caused by a lack of water for personal hygiene
  • Examples include: Dermatological disease such as scabies and Ophthalmic diseases
  • Also, Louse-borne diseases such as louse-borne typhus and relapsing fever.
• To prevent: provision of ample water and personal hygiene is essential
• Water-based diseases are caused by infectious agents spread by contact with water
  • Involves a life cycle stage in an aquatic animal
  • Humans infected through organism excretion

Water-Related Diseases

• Spread by insects that live close to water -Spread through mosquitoes, flies and other insects that near or breed from water -Malaria, sleeping sickness, yellow fever, dengue fever, filariasis, onchocerciasis are examples

Protection of Water from Contamination

• Rate of groundwater contamination depends on:
  • Aquifer nature, hydraulic gradient, water table depth, and distance from contaminant sources
• Well water contamination may be the contamination of wells by contaminates from nearby privies, cesspools, septic tanks, polluted surface water, pollutants such as microorganisms or animal and or from unsanitary drawing equipment

Well Protection

• Requires well siting and protection by:
  • Casing of at least 3m depth and 60cm above ground, concrete cover, sanitary water drawing and fencing to prevent contaminants
  • Also needs a diversion ditch to guide flow away from the well

Spring Protection

• Requires sanitary survey before development of spring
• Followed by waterproof concrete protection box construction over spring to prevent pollution
• Collection box construction enables adequate storage of water supply
• Build retention wall in box front to hold water in delivery pipe Install cleaning/washing drainpipe
• Screening intake and overflow pipes to prevent flow blockage by gravel/animals
• 10-15 meter radius diversion ditch to direct rain away

Surface Water Protection

• Protection of streams from gross pollution means:
• Avoiding or drastically reducing the dumping of municipal waste or animal wastes factories wastes etc.
• Zoning stream; uppper most section is for drinking purpose and Lower section is for washing and domestic animals

Water Treatment

• The processes that remove dangerous or undesirable biological, chemical, or physical substances from water intended for drinking
• Main objectives: Remove pathogens, substances that impart color, taste, or odor, Chemicals or minerals, also regulate essential elements and/or dissolved gasses
• Small scale (Household water treatment of using boiling, water filter systems and/or chemical or solar disinfection, but the steps for large scale water treatment (Municipal water Treatment) are different.

Small Scale Water Treatment

• Household water treatment of water filters or disinfection can be attained by different means, the most common being:
• Boiling
• Recommended for 1 minute, adding 1 minute per 1000 elevation meters, kills pathogens at 100°C, the world's oldest
• Chemical disinfection
• Liquid chlorine is most commonly and widely applied chemical solution because of its local availability, affordability ease of use.
• Sodium dichloroiscyanurate (NaDCC) tables in unit purchases of 10 tablets for 10 days that expire after 5 years
• Disinfection
• SODIS relies on sunlight to kill pathogens in small amounts of low turbidity water Households fill transparent, non-colored polyethylene terephthalate bottles and leaving in sunlight for 1 hour at 50°C

Filtration

• Bio-sand Filters
• A concrete or plastic box filled with sand and gravel, and collects the filtrate into a safe container and pathogens and turbidity are removed.
• Kanchan Arsenic Filter
  • Layer or rusty nails removes arsenic, with brick chip on top to keep the nails from moving aorund
  • The Pathogens and turbidity are removed by physical and biological processes.
• Life-Straw
  • A cartridge contains a membrane filter (20 nanometers) that removes pathogens.
• Ceramic Candle Filter
• Filters by Hollow cylinders of of combustible material

Large scale water treatment (Municipal water treatment) and it's steps

• Ground water treatment: Aeration → Disinfection →Storage➔ distribution
• Surface water treatment: Screening → Coagulation→ Mixing -> Sedimentation➔ filtration->disinfection ->Storage distribution
• It can be aided by processes of:
  • Aeration which reduces substances that cause color, odor and taste
  • Sedimentation which makes water is made quiescent to allow heavy particles deposited

Flocculation or coagulation and Filtration

• Floc/Coagulation removes Color, bacteria and most commonly uses Aluminum sulphate (Alum), ferrous sulphate
• Filtration removes 97%-99% of the bacteria, by using slow/rapid/pressure filters.
• Disinfections destroys/inactivates harmful microorganisms, via;
  • Physical disaffections using Boiling and UV lights
  • Chemical disaffections effective kill microorganisms via chemical disinfectants chlorine chemicals like: Chlorine and Chlorine compound, lodine, Ozone.
• Chlorination Uses Calcium hypo chlorite powder and Sodium hypo chlorite solution
  • The amount of chlorine used is called Chlorine Demand and the Residual chlorine the amount left over-is used to measure the chlorine demand amount

Water Testing

• Important parameters: Physical, chemical, and microbiological
• Physical
  • Caused by turbidity, color, taste, or odour along with the waters PH
• Chemical contains hardnesses causes by Ca and Mg
  • Can be temporary an removed by boiling or Permanent and caused by sulphates
• Contains Water hardness categories between soft, moderately hard, Hard and very hard which can be caused by soil formation
• Microbiological consist of water, bacteria, viruses, faces and E.coli