DHAN Biosand Filters

Target SDGs

Market Suggested Retail Price

$20.00

Target Users (Target Impact Group)

Household

Distributors / Implementing Organizations

DHAN Foundation

Competitive Landscape

Direct competitors include Hydraid® BioSand Filter.

Countries

India

Manufacturing/Building Method

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.

Intellectural Property Type

Open-source

User Provision Model

Users can contact the DHAN Foundation directly.

Distributions to Date Status

As of 2014, 3500+ Biosand Filters installed.

Design Specifications

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.

Product Schematics

Technical Support

DHAN foundation conducts training workshops, provides manual and CD for technical assistance. A detailed technical manual is available by CAWST as well.

Replacement Components

All the manufacturing and replacement components are intended to be available locally; including sand, concrete, and PVC piping.

Lifecycle

30 years

Manufacturer Specified Performance Parameters

This biosand filter removes iron and manganese and has >97% pathogen removal efficiency.

Vetted Performance Status

Water samples of 50 DHAN Biosand filters tested in India for microbial performance showed >80% pathogen removal efficiency. Additionally, there have been many laboratory and field tests performed on with Biosand filters; including quality control in the production of Biosand filters in Zambia.

Safety

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.

Complementary Technical Systems

Suitable containers for water storage.

Academic Research and References

Compliance with regulations

Unknown

Evaluation methods

Field and laboratory evaluation in Haiti. Also, the manufacturer tested for microbial contamination using Oxfam Delagua Test kit.

Other Information

CAWST Blog India: Bold Hearts- The Village of Women