Water is essential for human survival on Earth and in space. A typical person requires between 3.5 to 15 liters per day. Yet launching large quantities of water up to the International Space Station (ISS) is terribly expensive, and would be a major impediment to future space settlement. So NASA has made water recycling a vital part of closing the life support “loop”. Meanwhile, water is often in short supply even on the Earth, especially in a clean, drinkable form.