iSSF (Intermittently Operated Slow Sand Filtration System)

Target Countries

Cambodia, Congo (Kinshasa), Kenya, Nicaragua, Philippines

Target SDGs

Market Suggested Retail Price

$10,000.00

Target Users (Target Impact Group)

Community

Distributors / Implementing Organizations

This product has been implemented by Centre for Affordable Water and Sanitation Technology (CAWST), Samaritan’s Purse Canada, and Clear Cambodia.

Competitive Landscape

Direct competitors include Jal-TARA Water Filters.

Manufacturing/Building Method

The iSSF is built from locally-available materials such as water supply tanks, PVC pipe, and sand. The iSSF Manual is free to download.

Intellectural Property Type

Open Source

User Provision Model

This product is provided by aid organizations who work with communities and/or schools to build the system.

Distributions to Date Status

Due to the open source nature of the product, an exact number of distributions to date is unknown. However, Clear Cambodia have installed 900 school iSSF filters as of July 2020.

Design Specifications

The iSSF is operated by filling the reservoir tank with dirty water. Water flows from the reservoir tank into the filter tank via PVC pipe. The water is gravity fed though the biolayer, sand, and under drain layers in the filter tank. The water then flows through a PCV pipe to the storage tank.

Product Schematics

Technical Support

Technical support to organisations and individuals is provided by CAWST.

Replacement Components

Replacement components are locally sourced.

Lifecycle

10-15 years

Manufacturer Specified Performance Parameters

The filter was designed for a Hydraulic Loading Rate of 1.6 L/min for a cylindrical tank of 1 m diameter, to provide sufficient yield and quality of water.

Vetted Performance Status

Testing performance by CAWST, during a field evaluation in Cambodia, determined 75% of the sampled iSSF filtered water presented zero E. coli and 95 % of stored water presented <10 E. coli. This is further described on page 52 of the iSSF manual.

Safety

The filter should be monitored and maintained regularly to ensure safety. Instructions for maintenance are provided in the iSSF manual.

Complementary Technical Systems

Adding chlorine to the outlet tank can increase the safety of the water.

Academic Research and References

Compliance with regulations

This product complies with the WHO turbidity reduction standards.

Evaluation methods

This product has been evaluated for E. Coli and turbidity reduction through field testing in Cambodia.

Other Information

None