Modular Water Storage: Research Findings


After visiting Longido, Tanzania, my project has taken on a new direction. Two major findings have affected my project:
  1.  I found that eaves-troughs were far more prevalent than previously thought. Further more, eaves troughing was available in more sophisticated forms than cut-PVC-pipes that were noted in earlier research. While many issues existed with the eaves that were in place (they were held together with duct-tape, they leaked, the most efficient ones seemed too expensive for the average user and not all users had even a simple version), an even more prominent issue remained -- storage for the collected water was highly inadequate. After seeing that many eaves troughs directed the water to the ground with no intent for storage, and finding that most individual homes lacked any form or personal storage, it was decided that the project should focus on rain water storage.
  2. My original research had guided me to focus on simple / basic materials that could be easily sourced. However, after arriving in Longido, it became apparent that distribution networks did exist; nails, lumber, tarps etc were not manufactured in Longido, but shipped in from near by cities. I noticed large plastic tanks that appeared to be roto-molded were common in many public areas. After some inquiry I found that these tanks were being manufactued in Tanzania for Tanzanian residents. AND a prominent, advanced manufacturer was located in Arusha, only a few hours away! This changed my attitude towards materials use and how to make things local. The tanks could easily be manufactured and mass-produced using plastics molding technology while still meeting the criteria for the project to stay local. 

I had many observations about the tanks that were present in Longido. The concrete tanks especially were problematic: 
  • They must be produced one at a time, on site. Each tank requires the building of a mold and dedicated construction time
  • Larger quantity of materials required, shipping materials to site can be costly
  • Low quality cement is being used
    • cement deteriorates and maintenance is difficult, cracks in cement foundation are difficult to fix
    • cement interior may crumble into water and contaminate water
  • Very permanent and not always built in positions that make sense in respect to the rest of the building. Not easy way to replace tank if needed
  • Many people believe that cement is better than plastic – mental barriers need to be overcome
  • people believe plastic will deteriorate in sun, but this is not as likely

The plastic tanks had issues of their own:
  • Most people in Longido were unaware of the Arusha Manufacturer (Lodhia), causing them to purchase tanks from a company in Nairobi, leading to high shipping costs
  • Shipping costs were even higher due to the lack of nesting; tanks were large and sealed and only 5 (approx) could be shipped at a time
  • The tanks appeared too costly for the average person, and popular sizes were massive / too large for residential areas 
  • There was no easy way to increase the amount of storage over time 
  • No visual indicators exist to display how much water is in the tank. However, a clear window is not viable as this can cause algae growth 
Overall, however, there seems to be more potential with the plastic tanks than concrete, especially because plastic can be mass produced in a more cost effective way. 

I spoke to many individuals about the issues they faced surrounding water storage and NGO projects. Some of the main findings were: 
  • There is a major need for local materials to be used in NGO projects
  • pilot projects work best. The project should be designed in a way that allows users to see the project in action in a local public space; this gives them a chance to explore the project themselves before completely buying in
  • cost is a major issue to be considered, how do we ensure that individuals will be able to afford it, how can we ensure that a public space could fund it, etc?
  • How can we improve water collection from grass roofs. Grass roofs are particularly problematic as they often carry insects and bacteria
  • People are fond of the portability of plastic bins
  • schools are seen as very valuable, and can act as potential hubs for pilot projects
  • Questions asked
    • How does the tank overflow from one tank to the next?
    • How does the water get filtered?
  • Mixed feelings about how the water should be filtered / filtering the water as a secondary action
  • There is a feeling among certain members of the community that the leaders should be responsible for ensuring that their community understands the technology

Some of the questions I still need to answer include: 
  • What materials are best? Plastic?
  • Should it be roto-molded or injection molded?
  • Should I still consider cement?
  • What about lightweight plastic bags?
  • What form factor will both nest and stack?
  • what to do with lids when they aren't in use?

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