Probably a "water maker" for a boat, my understanding is that they use reverse-osmosis to desalinate water, so it's easier to have them take up small amounts of

Probably a "water maker" for a boat, my understanding is that they use reverse-osmosis to desalinate water, so it's easier to have them take up small amounts of extra load. It's a nice self-contained unit that you can start and stop pretty much instantly.