Ideas at Work (IaW) Round Biosand Filter is a product for providing improved quality water to rural communities in Cambodia.
This product is discontinued and no longer in production.
SDG 6: Clean Water and Sanitation
Target Users (Target Impact Group)
Distributors / Implementing Organizations
Ideas at Work
The Round Bio Sand Filter is manufactured on demand via a mould unit. The main parts of the mould unit are shown in the exploded view below are: 1) the puller, 2) an inner mould, and 3) outer mould. The mould is bolted together, turned upside down and fitted with a copper outlet pipe. A concrete mix is then poured in the mould and compacted down. After several hours the puller is used to remove the inner mould after which the outer mould can be removed revealing the finished filter shell. The filter is then filled with sand and gravel layers. The mould is bolted together, turned upside down and fitted with a copper outlet pipe. A concrete mix is then poured in the mould and compacted down. After several hours the puller is used to remove the inner mould after which the outer mould can be removed revealing the finished filter shell. The filter is then filled with sand and gravel layers.
Intellectural Property Type
User Provision Model
No longer available for purchase.
Distributions to Date Status
Target use case
Manufacturer-specified flow rate (L/hr)
More than 99.9 removal under laboratory testing
70-99% removal under laboratory testing
Heavy metals and/or arsenic reduction
Maximum recommended influent turbidity level (NTU)
Effluent turbidity levels (NTU)
85-95% turbidity removal
Manufacturer-specified volume between cleaning (L)
Material of construction
The IaW Round BSF is based on a design by MedAir and has a ‘round’ form instead of a ‘square’ form typical of most BSF units, reducing the mass and material costs of the unit. This design also makes it easier to move the unit by rolling it on its bottom edge. This is achieved by relatively simple modifications to a standard round cement drain pipe moulds. To operate the IaW BSF, contaminated water is poured into the unit at the top. The water passes through the diffuser plate and the sand and gravel layers. Head pressure pushes water through the copper 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. The typical flow rate of the unit is around 60 L/hr. Dimensions of the finished BSF: Outer diameter: 35 cm; Inner diameter: 30 cm; Height: 95 cm; Weight: 60 kg Dimensions of the finished BSF: Outer diameter: 35 cm; Inner diameter: 30 cm; Height: 95 cm; Weight: 60 kg
Users are responsible for maintenance and repair.
This is no longer in production.
Manufacturer Specified Performance Parameters
The typical flow rate of the unit is around 60 L/hr.
Vetted Performance Status
The Biosand Filter (BSF) is a proven technology, which removes pathogens such as bacteria, protozoa and helminth. BSFs are also somewhat effective for the removal of virus (CAWST 2009). Physical parameters such as turbidity and iron are also eliminated from drinking water. However, dissolved chemicals (such as organic pesticides or arsenic) are not removed. The treated water generally has an agreeable colour, taste and odour. The table below shows the biosand filter treatment efficiency in removing pathogens, turbidity and iron (adapted form CAWST 2009). Additional BSF evaluations have been aggregated by CAWST and include randomized controlled trials and field studies. Additional BSF evaluations have been aggregated by CAWST and include randomized controlled trials and field studies.
No cited hazards.
Complementary Technical Systems
Safe water storage.
Academic Research and References
Significant research has been conducted on BSF technology. A comprehensive list is available via CAWST.
Biosand filter literature summary – CAWST
An Assessment Of Continued Use And Health Impact Of The Concrete Biosand Filter In Bonao, Dominican Republic – American Journal of Tropical Medicine and Hygiene
“Biosand Filter,” Sswm.info. Available: https://sswm.info/water-nutrient-cycle/water-purification/hardwares/point-use-water-treatment/biosand-filter
Compliance with regulations
Although Biosand filters are known to reduce pathogen load in drinking water, this technology does not consistently meet WHO requirements.