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[[Image:CAWST_Kachan.png|thumb|right|150px| Cross-section through a Kachan Arsenic Filter]]
The Kanchan Arsenic Filter (KAF) is an adaptation of the biosand filter (BSF). In addition to providing microbiological water treatmen, the It is based on slow sand filtration and iron hydroxide adsorption principles. The KAF has been designed to remove arsenic from drinking water, in addition to providing microbiological water treatment. Arsenic removal is achieved by incorporating a layer of rusty non-galvanized nails in the diffuser basin of the filter. The {{procontable | pro=- Can remove arsenic, pathogens, iron oxide adsorbs and turbidity from drinking water <br>- Constructed by trained local technicians using local materials. <br> - Good flow rate (15-20 litres/hour) <br>- Simple operation and maintenance (O&M) <br>- This KAF is constructed of simple materials available on the arsenic from local market <br>- The construction of the filter can be carried out by locally trained technicians <br>| con= - Does not provide residual protection to minimize recontamination <br>- Filter should not be removed after installation because cracking or breakage may occur. <br>- Waste isolation <br>- Changing watersources (esp.to rainwater) may compromise removal of arsenic <br>}}
==History and social context==
This filter was developed by researchers at Massachusetts Institute of Technology (MIT), Environment and Public Health Organization (ENPHO) of Nepal, and Rural Water Supply and Sanitation Support Programme (RWSSSP) of Nepal.
==Suitable conditions ==