Abstract
Instead of being a customer of PDAM, as the local drinking company, in order to get access to piped clean
water supply system, there are around 10% of more than 100 million citizens decided to joint participation
into a community based water supply system. Hence, the questions are: Why people join, or not join, in the
community-based water supply system for access to water? How do social influence processes give effect to
their choice to access community-based water supply system? The hypothesis is people with better
community ties have ability to organize community-based water supply system. In respect with an empirical
research in Singosari district, Malang regency of East Java Province, this research investigates the answers
through (i) Centrality in Social Network Analysis which explains social structure of the community and (ii)
spatial econometric approach through Spatial Autoregressive (SAR) Probit Model which expresses effects of
social interaction among households.