| Abstract | The United Nations has set Millennium Development Goals (MDG) which issue on water and sanitation. To reach this goal each country has to improve water and sanitation facilities. The key aspect of this study is on financial analysis because financial consideration is often used as the first step in planning and selecting projects but for the sanitation systems is generally weak. In this study, Life Cycle Cost Analysis (LCCA) is brought to determine the cost of on-site sanitation systems because it is estimated cost from early stage to final stage of the project. Net Present Value (NPV) and Benefit-Cost ratio (BCR) and payback period are supplementary to LCCA with three sustainable determinants (economic, environmental and health). In this study, three types of onsite sanitation systems (cesspool, septic tank, biogas digester (fixed dome)) in Klong Luang Municipality were assessed. The results indicated that for economic determinant, cesspool is the cheapest system in both of investment cost (44 USD/capita) and future cost (operation and maintenance cost) (1,400 USD/capita) over 35 years expected life span at household level, while septic tank and biogas digester (fixed dome) invest of 210 USD/capita and 200 USD/capita respectively and future costs 1,400 USD/capita and 9,000 USD/capita are more expensive. For environmental determinant, in household level, septic tank and biogas digester (Fixed dome) can save cost of water pollution reduction (2,900 USD/capita in both systems) higher than cesspool (2,170 USD/capita) due to higher water pollution reduction. However, biogas digester can reduce methane emission due to the use of biogas in kitchen with benefit from CERs trading (38 USD/capita) and LPG cost saving (4,860 USD/capita) over 35 years of expected life span. At community level, the exiting condition (2,940 USD/capita) could save water pollution reduction cost at lower rate than the improved systems (3,620/ USD/capita). Furthermore, in the improved condition could earn benefits from CERs trading and LPG cost saving which are 50 USD/capita and 4,800 USD/capita respectively. For health consideration, diarrhea is a major disease due to poor sanitation which people could have loss their money due to suffering diseases. Moreover, the health problems were related to personal hygiene practice and behavior. In conclusion, as comparison centralized wastewater treatment plant, the most attractive sanitation technology is onsite sanitation systems which is septic tank which had high NPV and BCR are 6070 and 4.74 while biogas digester (fixed dome) (338 and 1.36) and cesspool (3,220 and 3.21). |