Rooftop Rainwater Harvesting: A study of related technologies and attitudes Dar es Salaam and Bagamo

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Rooftop Rainwater HarvestingA study of related
technologies and attitudes Dar es Salaam and
Bagamoyo, Tanzania

• Stephanie Sims, MBA Candidate
• stephanie.a.sims_at_cba.ufl.edu

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Agenda

• Water Issues in Africa
• Coastal Tanzania
• Water Supply and Demand
• Rainwater Harvesting
• Rainfall in Africa
• Technologies
• Case Studies
• Economic and Social Barriers
• Opportunities

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Water Issues in Africa

• 1.1 billion people (18 percent of the world's
  population, including 1/3 of Africas
  population) lack access to safe drinking water.
• More than 2 million people in developing
  countries (most of them children) die each year
  from diseases associated with unsafe drinking
  water, inadequate sanitation, and poor hygiene.
• On average, women and children in Africa walk 4
  miles a day carrying 5 gallons of water. This
  keeps women from other productive tasks and
  prevents many children from going to school.
• Accounts to 40 billion working hours a year

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Dar es Salaam and Bagamoyo

• Coastal Region
• Dar es Salaam Population 3.5-4 million
• One of the fastest growing cities in Africa
• Major East African Port
• 70 slums
• Bagamoyo Population 30,000

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Dar es Salaam and Bagamoyo

• Water supply handled by DAWASCO water utility.
• Limited water connections, especially in slum
  areas
• System cannot accommodate growing population
• Collect payment for only a fraction of water used
• Piped water is not enough to meet demand
• Poor infrastructure and illegal use contribute to
  losses
• Imposed rationing Connections have running water
  only twice a week
• Storage tanks are common for those who can afford
  them
• Middle and high income earners can afford to dig
  wells

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Water Costs

• DAWASCO provides the cheapest clean water
• 0.30/1000 L
• Water kiosks are available in some areas not
  serviced by DAWASCO
• 3x higher price
• Supplemented by water vendors at higher prices
• 14x higher price

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Rainfall in Africa

• Green Low rainfall
• 200-750 mm
• Pink Medium rainfall
• 750-1200 mm
• Purple High rainfall
• gt1200 mm
• 2006 UNEP Report
• Rainwater Harvesting is beneficial in areas with
  gt200 mm rainfall

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Rainfall in Africa

• If rainfall is taken into account, Africa is not
  water scarce. (Currently 14 African nations are
  classified as water scarce)
• Rainfall contribution is more than adequate to
  meet the needs of the current population.
• Africas water crisis is more an economic problem
  from lack of investment than a matter of physical
  scarcity.
• It is paradoxical to allow rainwater to runoff
  and cause environmental problems such as
  flooding, landslides, and soil erosion while it
  is possible to harness the water for use in
  households, agriculture, and industry.

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Rooftop Rainwater Harvesting

• System Components
• Roofing material
• Gutters- Catchment
• Pipes
• Storage Tank
• Enclosed to prevent contamination
• Pump- to elevated tank
• Filter-Treatment for Potable Use
• Simple screens on pipes
• Most commonly chlorine tablets

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Household Scale RWH

• Corrugated iron roof
• Simple metal gutter
• Plastic barrel for storage
• Water is untreated- used for non-potable purposes
  only

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Household Scale RWH

• PVC pipes and gutters
• Underground storage tank
• Pump and elevated tank
• Treated for Potable Use

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Commercial Scale RWH
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Commercial Scale RWH

• Kariakoo Market (1974)
• Roof made of 20 funnels leading to large
  underground storage tanks

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Economic and Social Barriers to RWH

• Social stigma of using free water
• Perceived quality concerns
• Rainwater lacks the minerals of groundwater
• Perception of being acidic or dirty from roofing
• Systems should be cleaned annually before the
  rainy season
• Very safe when compared to traditional water
  sources
• Large initial capital investment
• Microfinancing could alleviate pressure on
  individuals

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Benefits of RWH in Africa

• RWH provides water in a decentralized manor
• Avoids inefficiencies and costs of infrastructure
• Centralized piping is not economically viable in
  many areas
• The areas with lowest population tend to be the
  most disadvantaged, where RWH would have the
  greatest impact.
• Saves women and children time spent fetching
  water
• Reduces/eliminates cost of water
• Helps attenuate stormwater and prevent
  environmental problems related to runoff

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Opportunities

• Renewed NGO focus on providing clean water
• UNs Millenium Development Goals call for halving
  "by 2015, the proportion of people without
  sustainable access to safe drinking water and
  basic sanitation."
• 2005-2015 declared the Water for Life Decade
• Rainwater Harvesting in Africa
• High feasibility with existing technologies
• Household and commercial applications
• Economic and social barriers to overcome
• Potential for RWH Application Worldwide

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Questions?