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Earth/water facts:
- 71% of the earth's surface is covered with water
- 97.5% is found as salt water in seas and oceans
- Only 2.5% of Earth's water is freshwater
- 70% of fresh water is locked in glaciers are polar ice caps- unavailable
- Much of remainder is soil "moisture" or locked in deep aquifers unavailable
- Less than 1% is freshwater in rivers, lakes, and streams
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Available Freshwater for Humans
0.007%
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More Water Facts
- Human body is 65% H2O
- Humans require between 1-3 liters of fresh water per day to drink
- 50 liters per day is considered the bare minimum a human needs daily
- Avg. person in US uses >500 liters/day
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Water Consumption
- Agriculture- largest user of water (60%)
- Industry (15%)
- Housholds (25%)
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Groundwater
- Makes up 20% of worlds fresh water suply
- Usually cleaner and purer than surface water sources
- Soil filters out bacteria and other contaminants
- Dependable supplies because there is no evaporation
- Now threatened by pollution and overuse
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Groundwater Pollution
- Can be chemical, biological, or radiological
- Amendments to the Safe Drinking Water Act of 1986 cover contaminants in public water systems, but not the approximately 12 million private wells in the US
- 58% of waterborne disease outbreaks between 1971-2006 traced to microbially contaminated groundwater
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Groundwater Pollution
- Waste storage or treatment facilities
- Chemcial Industrial Activity
- Septic systems
- Sweers, oil pipleines, accidental spills
- Irrigation, mine drainage, farm chemicals, manures, substances applied to roads
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Wars over Water?
- Water demand is increasing with population growth, but water supply is finites
- Darfur- 400,000 deaths (farmers vs. nomads)
- Gaza- More than 1 million share one aquifer
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Developing World Differences
1.5 billion people still access to safe drinking water
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South America
- Amazin basin in S. America contains 20% of Earths freshwater
- 50-90% of water lost through leaky pipes
- Waste and Population; Increasing populations means cities must rely on sources much farther away
- MOre than 140 million people have no safe drinking water in their homes
- Private for Profit Companies- three companies now provide water for 300 million people. Outrageous rates, reduced water quality, huge profits
- In bolivia Bechtel Crop busted up rain catchers, claiming they now owned rain
- Thousands rioted, and the new Bolivian govt. canncelled Bechtels contract
- Bechtel now owns the water infrastructure and distribution contract for post war Iraq
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Mega Dams
- Benefits: Irrigate crops, control flooding, cheap clean power, recreations
- Consequences: Alter ecosystems, change fish stocks, chinese river dolphins, loss of high quality agricultural land, loss of small towns, resettlement of people, loss of archeological sits/fossils
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Clean Water Act, 1972
- No one has the right to pollute
- Pollution continues due to technological limits and economic blackmail
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US Pollution Facts
- Too polluted for swimming or fishing
- 40% of rivers
- 46% of lakes
- 2/3 of all estuaries
- In any given year, about 25% of beaches in the US are under advisories or are closed at least one time because of water pollution
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Most Polluted US rivers
- Mississippi River
- Ohio River
- Tennessee River
- Ward Cove
- Savannah River
- Delaware River
- Thanmes River, CT
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Types of water pollution
- Point Source: Industry
- Non-Point source:
- Agriculture
- Construction
- Urban street runoff/country dwellers
- acid mine drainage
- airborne pollutants
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Wastewater treatment
- POTW (Publicly owned treatment works)
- serve 70% of the US population
- Prevents Disease
- Water Re-Usage
- In average US community each person uses 100 gallons water/day/person
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Sewer Treatment (Primary Treatment:)
- Removal of large debris
- Aeration
- Sedimentation and sludge removal
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Sewer Treatment: Secondary
- Microorganisms added to decompose wastes
- Disinfection (chlorine)
- Dechlorination
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Drinking Water
- Oregon: 75% citizens get their drinking water from public water systems
- US: 53% surface water, 46% groudnwater
- Surface Water: Rivers, lakes, reservoirs
- Ground water: pumped from wells drilled into aquifers
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Bottled Water
- Advantages:
- Only alternative for contaminated wells
- Safe supply in case of emergency
- Disadvantages:Expensive (10,000X higher)
- Consumes ernergy and resources
- Potentially dangerous (75% of bottled water not regulated)
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