To achieve universal access to safely managed drinking water as stipulated in Sustainable Development Goals (SDGs), it is necessary to secure the financial resources and to promote effectiveness of the investment. This study aimed to estimate the socio-economic factors to affect the progress of access to at least basic drinking water services and effectiveness of the ODA in Millennium Development Goals (MDGs) era. Per capita Gross National Products (GDP) and Human Development Index (HDI) was associated with the prevalence rate of access to at least basic water services while the other factors as ODA may have significant role to determine the progress of the access. Average capital investment cost (as capital expenditure, CAPEX) was estimated to be 365 USD per capita (148 to 931 in 95% confidence interval) as a population weighed mean value for 17 low to middle income countries. Necessary capital investment to achieve universal basic access by 2030, based on the capital investment cost per capita, was estimated to be 5.46 billion USD/year, implying that further investment from both ODA and other financial resources are necessary.