The water “business” involves large numbers of consumers using water in different ways including households, industries, and farms. Management of water at the user level, and the associated collection of charges or fees, carries a potential corruption risk. This U4 Brief focuses on the risks at the service provider-consumer interface associated with these small but numerous transactions, and how donors may help prevent so-called petty corruption. The related losses of revenue and harm to consumer confidence can seriously threaten the financial sustainability and viability of service providers.