. In this study examination of label information physical and microbiological qualities was performed in 30 clear-plastic and 3 opaque-plastic bottled drinking water products distributed in city municipality of Ubon Ratchathani. Results showed that 12 clear-plastic (36%) and 3 opaque-plastic (9%) bottled drinking water samples had no expiry date on the product labels which were discordant to the criteria for drinking water in sealed containers imposed by the Ministry of Public Health of Thailand no. 383 (2017). Odorless appearances of all drinking water samples were observed. Values of pH in 4 clear-plastic (12%) and 3 opaque-plastic (9%) bottled drinking water samples were in the ranges of 6.21±0.00–6.29±0.03 which were below the allowable limit (pH 6.5–8.5). All bottled drinking water products contained numbers of total coliform and fecal coliform bacteria less than 2 MPN/100 mL and were devoid of E. coli. Therefore based on the quality of clear-plastic and opaqueplastic bottled drinking water products distributed in city municipality of Ubon Ratchathani 1 5 samples (45%) did not meet standard for drinking water in sealed containers declared by the Ministry of Public Health of Thailand (1981 and 2017) owing to no expiry date labeled on the products and pH value below 6.5.

The objective of this research was presented a decision support making process for efficiency improvement of drinking water processing using retrofit technique for machine and equipment rehabilitate. This methodology was applied Analytic Hierarchy Process (AHP) for selecting an appropriate maintenance sub-contractor. To complete the research existing water purifying machine and tools were inspected to assess its capacity. Future capacity of the purifying machine was also identified. Consequently machine and tools such as water tank and water filter were inspected for retrofitting for the example water tank water filter water quality control and bottle packing. Finally the analytic hierarchy process was utilized to select the most appropriate maintenance sub-contractor. In this process both qualitative and quantitative processes were analysed. The result of this research has been found that this multicriteria decision making process could be used to support the decision making investment process of water purification retrofit unit at Faculty of Engineering Rajamangala University of Technology Phra Nakorn efficiently. Furthermore it could be reduced bias from decision makers while the decision was accepted by all stakeholders.