America’s substantial water challenges are not secret any longer. Cities poisoned by lead-contaminated drinking water and toxic algae, along with crippling droughts and dwindling groundwater reserves, make it increasingly clear that the nation’s water systems urgently require an overhaul. That was the consensus view of experts convened this week in New York City during H2O Catalyst, an interactive town hall event broadcast live by Circle of Blue with American Public Media and Columbia University.