Hydraid® BioSand Filter
E. Neal Caldwell, John Kevin Hodges
Hydraid is a plastic bodied biosand filter used to purify water.
The Hydraid® BioSand Water Filter is a patented, lightweight, household, point-of-use filter powered by gravity. The filter design is inspired by the open-source BioSand Filtration technology but uses a lightweight plastic housing instead of concrete. It is suggested that this technology is more portable, scalable and affordable compared to traditional concrete filters.
Today there are more than 75,000 Hydraid water filters in 46 countries. Specific countries are unknown.
Triple Quest – a collaborative social enterprise between Cascade Engineering and The Windquest Group (a West Michigan private investment fund) partners with entrepreneurs and NGOs in the developing world to make the Hydraid biosand filters available. Hydraid works with the local organizations to import the plastic containers, create the sand filter, and educate users.
Membrane filtration systems, Community scale purification systems, Point-of-use filtration equipment, Chlorination and other Biosand Filters
Goal 6: Clean water and sanitation
Households without access to clean water.
Mass-production of extruded plastic containers combined with manual assembly of sand/rock media. Manufacturing led by NativeEnergy.
Patented product. Patent number US8778175 B2
Available for bulk purchase to partner organizations via the social enterprise Triple Quest which partners with entrepreneurs and NGOs in the developing world to make the Hydraid biosand filters available. Hydraid works with the local organizations to import the plastic containers, create the sand filter, and educate users.
Today there are more than 75,000 Hydraid water filters in 46 countries.
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
The Hydraid® BioSand Water Filter is comprised of a plastic container that is filled with layers of sieved and washed sand and gravel. Water is poured into the top of the filter where it collects in a storage container. The water passes through the diffuser plate and the sand and gravel layers. Head pressure pushes water through the pipe in the base to the outlet point. Biological contamination is reduced through the actions of adsorption; mechanical filtering, predation (biological layer) and natural die off.
Height – 0.77 m (30.5″), Diameter – 0.42 m (16.5″);
Weight: Empty – 3.6kg (8 lbs.), Filled – 63.5kg (140 lbs.)
Technical support is expected to be provided by the user.
The plastic housing is available from the manufacturer while the filtration media is expected to be available locally.
Manufacturer estimates the lifecycle to be more than than 10 years.
The Hydraid® BioSand Water Filter manufacturer claims the following: Easy Installation: about 30 minutes (level and fill with sand). Filtering Capacity: 47 liters/hour. Serves the needs of 8-10 people daily. Prep Time: Surface biological layer forms naturally in about 2 weeks
In 2008, three health impact studies were performed specifically on the plastic Hydraid® BioSand Water Filter and involved 81 filters installed in Cambodian households, 89 in Honduran households and 115 in Ghanaian households.
In 2012 the health impact study on the plastic Hydraid® BioSand Water Filter showed greater or comparable reduction in diarrheal disease in comparison to trials of concrete biosand water filters in Cambodia, Kenya and the Dominican Republic.Link broken as of 2018
University of North Carolina and CAWST
Safe water storage container.
Significant research has been conducted on BSF technology. A comprehensive list is available via CAWST
Specific publications featuring the Hydraid BSF include: Stauber, C., Kominek, B., Liang, K., Osman, M., & Sobsey, M. (2012). Evaluation of the Impact of the Plastic BioSand Filter on Health and Drinking Water Quality in Rural Tamale, Ghana. International Journal of Environmental Research and Public Health, 9(12), 3806–3823.
Point of Use Household Drinking Water Filtration: A Practical, Effective Solution for Providing Sustained Access to Safe Drinking Water in the Developing WorldMark D. Sobsey, et.al., Department of Environmental Sciences and Engineering, CB#7431, University of North Carolina, Chapel Hill, North Carolina 27599-7431 Environ. Sci. Technol., 2008, 42 (12), pp 4261–4267. DOI: 10.1021/es702746n
The BSF unit’s medical-grade plastic is FDA approved for drinking water.
Lab testing of filtered water quality. Health impact studies have long been used to assess the impact of various technologies and investments in water, sanitation and hygiene interventions and are particularly useful as evaluation tools in understanding the interconnected necessity of water, sanitation and hygiene for health and development.
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