In the first paper of this two-part series on the development of a water sustainability index for West Java, a conceptual framework of West Java Water Sustainability Index (WJWSI) was developed. It consists of three main parts: components, indicators/sub-indicators and threshold values. This second paper of the series presents the application of the Delphi technique, followed by in-depth interviews with selected key experts, to refine the conceptual WJWSI framework. The Delphi application includes the design of the questionnaires, the selection of respondents, the distribution and collection of the completed questionnaires and the analysis of data. After Round One of the Delphi application, the respondents reached consensus for all proposed components in the conceptual framework. However, some modifications to the components were also suggested by few respondents. Regarding the indicators/sub-indicators, consensus for 9 of the proposed 12 indicators was reached, and 5 new indicators were suggested. For the threshold values, consensus was reached for threshold values of 5 indicators. In Round Two of the Delphi application, respondents were asked questions related to results from Round One, which include the modification on the components, indicators/sub-indicators which have not been agreed, and newly suggested indicators/sub-indicators and threshold values. Results of Round Two show that modifications on the components were agreed, and consensus was reached for 8 out of the proposed 9 indicators/sub-indicators. In terms of its components and indicators, the framework was then finalised in the in-depth interview with four key experts, selected from different respondent categories. For the threshold values not yet finalised, further study will be carried out, as there was not much input from the respondents in the Delphi application and the in-depth interview.