Joshi and colleagues tested homemade charcoal and activated-charcoal filter media for a portable point-of-use water filter intended for surface water and groundwater treatment in Nepal. This is a2 mitigation evidence: it reports filter-media design and water-quality changes before versus after charcoal-based treatment rather than a packaged-water occurrence survey.
Key numbers
The paper focused on total dissolved solids, electrical conductivity, pH, turbidity, ferrous iron, and arsenic. The abstract states that the charcoal cake showed around 40% reduction in ferrous-ion concentration when measured by UV-Vis spectrophotometry.
The authors report significant reductions in total dissolved solids, electrical conductivity, and turbidity after treatment through wood charcoal, activated wood charcoal, and the final charcoal-cake design. Wood charcoal was identified as the best-performing precursor among the tested charcoals and was then activated to improve performance.
The point-of-use concept was explicitly designed to be small, cheap, portable, and usable during travel or at the time of need.
Methods (brief)
Three charcoal precursors - normal wood, coconut shells, and corncobs - were combusted in a partially covered environment, ground, and tested as filter media. Surface-water and groundwater samples from Kathmandu Valley and Kavre district were analyzed before and after filtration for TDS, conductivity, pH, turbidity, ferrous iron, and arsenic. The final filter cake was designed as a personally portable treatment unit.
Implications
Certification: Do not use this source in product-occurrence or bottled-water concentration pools. It is remediation and point-of-use treatment evidence.
Courses: Useful for explaining low-cost household mitigation concepts and the distinction between source-water treatment performance and occurrence monitoring.
App: Context-only mitigation evidence for household arsenic and iron treatment strategies.
Wiki pages this source may touch
Verification notes
Recovered under the 2026-06-10 inclusion-by-default rule from a prior skip:not-food-occurrence disposition. The old skip was too narrow because the paper is direct point-of-use treatment evidence for arsenic/iron-bearing waters.
Products and ingredients are intentionally empty because the matrix is source water passed through charcoal filter media, not a market food or packaged-water product. The extracted text available in this run did not expose a fully legible table of arsenic before/after concentrations, so only numerically explicit statements visible in the extracted PDF are reproduced here.
Update history
The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.