Onsite household sanitation technologies such as septic tanks or latrines serve a large percentage of the world's population. Unfortunately, they experience high failure rates after construction, with resulting environmental and public health consequences. Previous work has suggested that these failures are often a result of our inability to navigate the technology--society nexus. In other words, they represent problems of social sustainability. In order to address this urgent problem, we build theory regarding the social sustainability of infrastructure systems by leveraging established organizational theory. To do this, we collect household level interview data in four communities in rural Bangladesh. Virtually all households in this research population have constructed onsite sanitation systems, typically using their own resources. However, almost half of these systems have since fallen into disrepair, mirroring the high socially based failure rates cited globally from similar systems. Using cross case qualitative analysis and legitimacy theory, we explored what differentiates those households that continue to use and maintain sanitation systems (those with socially sustainable systems) from those that do not (those with socially unsustainable systems). We found that households in the unsustainable group have adopted toilets ceremonially, with construction decoupled from the actual practice of maintaining and using the sanitation system. Understanding infrastructure abandonment as a form of organizational decoupling actually achieved) and competing rational myths (beliefs regarding how and why things ought to be done) drive decoupling and lead to abandoned sanitation. In order to recouple sanitation structure and practice for continued use and maintenance of onsite systems, designs should consider both effectiveness and competing rational myths. For example, by requiring odor management technology for all improved sanitation infrastructure we improve infrastructure effectiveness (by delivering odor management) and also address the commonly held rational myth of miasma (odors causing illness).