CAWST Biosand Filter (v10)¶
BioSand & Media Filters • Est. CapEx: $22.50 USD • Lifespan: 20 Years (Standardized)
Technical Overview¶
A household-scale, intermittently operated slow sand filter housed in concrete or sturdy plastic, using a layered bed of sand and gravel to turn unsafe water into safe drinking water. Over 2 million units have been deployed worldwide based on CAWST’s freely available open-source design, reaching deep into remote regions such as the Amazon delta.
Key Specifications & Engineering Parameters¶
| Parameter | Specification |
|---|---|
| Category | BioSand & Media Filters |
| Capital Cost (CapEx) | $22.50 USD |
| Power / Energy | 100% Gravity / Zero Power |
| Target Scale | Household (5–10 people) |
| Standard Lifespan | 20 Years (Standardized) |
| Technology Maturity | Commercially Available |
| Primary Mechanism | Water poured into the filter slowly percolates downward through a biologically active ‘schmutzdecke’ layer at the fine sand surface and subsequent sand bed. Mechanical straining, predation, adsorption, and natural biological processes in the established biofilm work together to reduce bacteria, protozoa, and turbidity using only gravity. |
Engineering Trade-Offs¶
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- Requires periodic community maintenance
- Site-specific hydrogeological constraints
Cross-Reference & Interactive Tools¶
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