Her enclosure is a simple plastic crate with a baking rack as a lid (my husband's ingenuity). Her drink bottle hooks over the side and she drinks when thirsty. Her bedding is ripped up newspaper (we simply keep the free local papers and use them) which is changed roughly ever 3 days. Rats do not smell, they are very clean, but the bedding has to be changed often. If we go away we simply give her to someone else for a couple of days and she's fine.
She is lovely, I highly recommend a rat if you want a low maintenance, cheap and rewarding pet.