Field Testing of Innovative On-site Sanitation System: Solar Septic Tank

Project Result / Case Study | 15 January 2019

The Asian Institute of Technology (AIT) has proposed to demonstrate the operational feasibility of a solar-powered septic tank as an alternative and sustainable sanitation option for communities. The increased temperature inside the septic tank will inactivate pathogens and reduce the environmental issues related to conventional fecal sludge management. In turn, this will improve the water quality of groundwater and surface water and minimize health risks.


Project site Thailand
Cost $124,200 ($75,000 PDA Grant; $49,200 AIT counterpart)
Status Ongoing
Approval date April 2017
Completion date 30 June 2019
ADB officer Michael White
Partner Asian Institute of Technology


For this pilot and demonstration activity, three solar septic tanks will be installed in Klong Slong municipality in Thailand and five in Cambodia as part of the Second Rural Water Supply and Sanitation Project – Additional Financing. In Thailand, where the households will likely have their own toilets, these will be retrofitted with the system. In Cambodia, complete units (toilet and solar septic tank) will most likely be installed.

Once the sites have been selected and tanks are in place, various performance indicators will be monitored, such as water quality of nearby groundwater, temperature distribution inside the septic tank, and effluent quality, among others. Following the technical evaluation of the solar septic tanks, stakeholders will be interviewed regarding their perception and satisfaction level.

Expected Results

With eight solar septic tanks to be installed by the end of the PDA, this will reduce contamination of groundwater and surface water, thus confirming the feasibility of using solar-powered septic tank as a an alternative sanitation option.

The projected environmental improvement could serve as a platform to create a policy brief in consultation with key agencies of the respective countries. It could also lead to replication in other communities and/or other countries in the region.