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Pathogens and suspended material are removed from the water through a combination of biological and physical processes. These occur both in both the biolayer and within the sand bed. These processes include: mechanical trapping, adsorption/attraction, predation and natural death.
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- Cement can be easily acquired in most developing countries. <br>
- People are familiar with the construction techniques using cement. <br>
- Household labour or volunteer labour can be utilized in the manufacturing process <br>
- The concrete container is heavy and durable. It does not need to be replaced as often as a plastic container <br>
- The spout piping is located inside the filter. Consequently, it is less prone to damage than a plastic filter, which has piping on its exterior <br>
- Plastic fabrication usually requires the importation of raw material or the finished product. Depending on your views of international trade, this can be an advantage or disadvantage. <br>
- The life expectancy of a plastic model is substantially less than a concrete model. The ultimate disposal of plastic is a concern for the environment <br>
- Encouraging and empowering local people to completely manage their own project increases local sustainability and motivates others to take action for safer water. This process can only be facilitated if the product supply is managed locally. In most cases, if a plastic model is used, there will always be a dependence on outside manufacturers and distributors to supply filters at a higher cost. <br>
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==History and social context==
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==Technical specification==