This chapter explores the relationship between corruption and the achievement of Sustainable Development Goal 6 (SDG 6) – ensuring clean water and sanitation for all. We begin by reviewing key literature on the impact of corruption in the water and sanitation sector. We then use a case study of the wastewater sector in Bangkok’s Extended Metropolitan Region (EBMR) to illustrate these issues in practice. Through interviews with key stakeholders, the chapter examines how corrupt practices, weak governance, and regulatory fragmentation hinder access to clean water and sanitation, exacerbating social inequalities. Finally, we offer recommendations aimed at improving transparency, strengthening regulatory frameworks, and empowering local groups to combat corruption and promote sustainable water management.