Litter box training rats is fairly simple, and really depends on the individual rats whether they'll pick it up or not. Females tend to pick it up better than males, and the younger the rats the better. Here at our rattery, the babies learn in their nursery cage from their moms (who are very good about using litter boxes), so should need minimal training on using the litter box. It's important to know that the ratties probably won't use the box 100% of the time, and they will still urinate around the cage (they are marking their territory).
Step 1: The box
We use hi-corner litter pans that can attach to the cage, which is best since the ratties can move the box around. The litter pan we use is available on the Cage Furniture page of Ratty Rat's Favorite Things. There are other brands and styles out there, and they'll all work great, but its best if they have a high back, and can attach to the cage.
Step 2: Location, Location, Location
Deciding where to put the litter pan is very important. It should go on the bottom level of the cage, away from the food, water, and shelter box and preferably in one of the corners away from the door. If you are starting with an existing group of rats and cage, put the box in the corner that the rats are tending to potty at the most.
Step 3: What litter to use in the box
This is perhaps the most important step, and it will make or break the potty training process. A different litter must be used in the litter box than is used in the rest of the cage. The rats need to be able to differentiate the potty from the rest of the cage.
If your starting with rats from our rattery, they are used to using Yesterday's New pelleted paper bedding in the litter box. You can switch them to a different kind, but it will have to be done in stages, start mixing the Yesterday's News with what you want to use, using more of the new kind of litter each time you clean the box.
If your starting with an existing group of ratties and cage, you'll need to use what ever litter or bedding you've been using in the whole cage, ONLY in the litter box, and get a new type of bedding for the rest of the cage. You can go back to using the old type of litter in the whole cage again, by slowly phasing in the new litter you'll be using in the litter box.
Step 4: Make the litter box dirty
When filling the litter box for the first time, fill it with the dirty bedding/litter from the cage. Clean the rest of the cage (really wash it well, deodorize it too if you can), and put the new, different bedding in the rest of the cage. By really "stinking it up", your ratties really get that THAT is the potty place.
Step 5: If they don't get it yet
If they still can't find the potty place and continue to potty all over the cage, place all the droppings that are outside the litter box INTO the litter box, and keep the rest of the cage super clean. Sometimes you'll need to completely remove any other bedding from the cage other than what's in the litter box.
Fleece can be added to the cage is you do this. In fact, fleece pieces can be used as a permanent bedding. It's not dusty at all, and doesn't add more trash to our landfills , and is fairly economical (remnants from fabric stores are great to use). The fleece will need to be washed every couple days, so make sure to get enough to last you several cage cleanings.
Also if they're still not using the box, pay attention to where they ARE going, and maybe move the box to that location.
Step 6: Maintaining
So now the ratties are using the potty fairly reliably. They still need help finding the potty. At least for the first few cage cleanings, only change about 50% of the litter in the litter box, or put a layer of dirty litter on top of the clean litter. Also continue to place any rogue litter droppings in the litter box. Over time they should continue to use the box more and more.
Step 7: Success!
Now you can clean your ratties litter boxes as needed without having to clean the entire cage. We change the litter in our litter boxes every couple days, and change the rest of the bedding once or twice a week as needed.
If you don't have success at this point, well, your ratties may be too stubborn and set in their ways. Some rats, especially older males, just don't get it.