edit: It's just like what you'd find in any modern commercial building in the US, just with a much older form factor of toilet. When we moved in I got curious why most new homes don't have them. Found out that they don't use any more water than a normal toilet, but they do require a higher water flow rate. The high flow rate requires at least a 2" water main into the house (which we have), while most modern residential construction uses a 1" or less.