You might think that creating ice may be a simple business: just throw water into the freezer and it turns to ice. Simple, right? That’s true if you only want to form one tray of ice, but most folks like better to have ice available on demand. That’s why we’ve ice makers, devices which will make ice consistently for the various years that you simply will own your fridge. The essential ingredient of ice is, as you would possibly expect, water. But you cannot just throw unspecified water into an ice maker: good ice needs clean, water.

Most ice makers are built around a tray that has semicircular depressions in it. A valve above this controls the flow of water, filling the tray with enough water to fill the depressions, forming the form of the cube. Because this tray is inside the freezer, it gets cold, and therefore the …