In the half century since the founding of the U.S. Environmental Protection Agency, the U.S. has spent nearly $5 trillion ($2017) to provide cleaner rivers, lakes, and drinking water, or annual spending of 0.8 percent of U.S. GDP in most years. Yet over half of rivers and substantial shares of drinking water systems violate standards, and polls for decades have listed water pollution as Americans’ number one environmental concern. We assess the history, effectiveness, and efficiency of the Clean Water Act and Safe Drinking Water Act, and obtain four main conclusions. First, water pollution has fallen since these laws, in part due to their interventions. Second, investments made under these laws could be more costeffective. Third, most recent studies estimate benefits of cleaning up pollution in rivers and lakes which are much less than their costs. Either these analyses systematically understate the value of these investments or these investments are inefficient. Analysis finds more positive net benefits of drinking water quality investments. Fourth, economic research and teaching on water pollution is surprisingly uncommon, as measured by samples of publications, conference presentations, or textbooks.