Filling a glass of water. Flushing the toilet. Washing dishes. These simple acts – which we do every day without thinking – only highlight our dependence on the remarkable-but-unremarked miracle that is our water supply and sanitation system.

To make these simple activities possible, we have built complex infrastructural and institutional networks that draw deeply on both historical practices and modern technology. Yet these systems are now facing a host of threats: chronic underinvestment, pollution, climate change, deregulatory pressures, institutional dysfunction, and rising costs. What will it take to live up to the promise of safe, affordable water and sanitation for all?