DHAN Biosand Filters are household sand filters developed by Canadian engineers promoted by DHAN Foundation. This household devices is build with local materials and filter water from wells, tanks, and oorani.
SDG 6: Clean water and sanitation
Households in India
DHAN foundation provides a training course to artisans and users to build Biosand Filters from locally available concrete and sand. DHAN also sells their own manufactured filters produced in 5 production centres in Tamil Nadu, India. Manufacturing instructions for Biosand filters are openly available from CAWST.
Users can contact the DHAN Foundation directly.
As of 2014, 3500+ Biosand Filters installed
Is this filter designed for individual, household, or community use?
Manufacturer-specified flow rate (L/hr)
Laboratory-evaluated log scale removal rate of bacteria
Laboratory-evaluated log scale removal rate of protozoa
Laboratory-evaluated log scale removal rate of viruses
Reduction levels of heavy metals and/or arsenic through this treatment system
Manufacturer-specified maximum level of inlet turbidity (NTU)
Range or value of outlet turbidity levels (NTU)
Recommended treatment capacity between cleanings
Description of materials of construction
Water is poured into the top of the DHAN Biosand filter and passes through layers of sand. The filtered water is collected in another storage container at the base. The pathogens are removed due to a combination of biological and mechanical processes. Between uses, a 5 cm deep layer of water is maintained above the sand all times,allowing for a biolayer to remain, which helps in the removal of bacteria and viruses. This feature distinguishes the Biosand filter from other slow sand filters.
The product schematics are shown in the image.
- Filter lid: Prevents contaminants from entering the filter.
- Diffuser plate: Protects the biological layer from damage when water is poured into the filter.
- Standing Water Layer: When the water stops flowing, a 5cm water layer is kept at the top which keeps the biological layer alive during pause periods.
- Filtration Sand: Traps organic and inorganic material at the top of the filter media.
- Outlet tube: Conducts water from filter base to outside.
- Medium Gravel/Course sand: presents fine sand from plugging drainage gravel.
- Drainage Gravel: promotes vertical flow of water into collector pipe. Prevents smaller gravel to block the outlet tube.
All the manufacturing and replacement components are intended to be available locally; including sand, concrete, and PVC piping.
This biosand filter removes iron and manganese and has >97% pathogen removal efficiency.
Important safety measures include: (1) Placing the filter inside the house on a levelled spot, (2) Cleaning the filter components and surroundings regularly, (3) Avoiding direct contact with spout and filter, (4) Measuring outlet flow rate from the sprout frequently to detect if maintenance is required
Suitable containers for water storage.
Several Biosand filter publications are available on CAWST website including:
Ngai, T.K.K. and Fenner, R.A. 2014. Designing programme Implementation Strategies to Increase the Adoption and Use of Biosand Water Filters in Rural India, Water Alternatives 7(2): 320-341
Wang, Narihiro, et al. 2014, MS2 Bacteriophage Reduction and Microbial Communities in Biosand Filters, Environ. Sci. Technol., 2014, 48 (12), pp 6702–6709.
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