ABSTRACT: At present, 99% of Thai people have access to basic sanitation facilities, but pollution from human wastewater and excreta poses serious environmental and health problems nationwide. Due to its high treatment efficiency and low investment cost, a solar septic tank has been developed as an innovative technology for domestic wastewater treatment. It is being considered as a new sanitation paradigm to fulfil the Thailand 4.0 policy and make a significant change in the country's environment to become a liveable society.