So, let's start with the number of litter boxes needed in the home. There is a rule... for each cat in the home, there should be one litter box plus one extra (the overflow box). This allows, hopefully, sufficient space for the eliminations of cats until the boxes can be scooped. Some cats have a strong preference to urinate in one area and defecate in another. Having an extra box allows for this preference. If you have a multi-level home, there should be at least one box on each level of the home. This provides kitty a chance to have his/her potty near in case of urgent need. Don't you like having a bathroom on the same floor you are occupying? Be aware too that having two litter boxes in close proximity, to a cat, is the same as one litter box. Place the boxes in different locations in the home.
Now, let's talk litter box size! So, you bring a new cat/kitten into your home, you stop by the pet store and get all your kitty needs as stated above. Some stores have a great deal of choice in litter boxes, others do not. Even where there is a great deal of choice, it may be related to type of box, not necessarily size of box. There are the basic plastic pans, covered boxes, corner boxes, litter systems, automatic boxes and now even flushing boxes. You would think with all this choice, the purrrfect box would be easy to find; right? Unfortunately, manufacturers are working to make kitty caretakers happy, not necessarily the cats. It seems many do not truly understand kitty's needs. It is important to consider caretakers' concerns; however, if cats' needs are considered and they are happy, then the caretaker's happiness will generally follow. Many of the litter systems, automatic and covered boxes are generally too small for cats to fit into comfortably. Most basic cat litter pans sizes are appropriate only for smaller cats. Did you know litter boxes should be 1 and 1/2 times the length of your cat?! If you've adopted a kitten or young cat, it may be appropriate to have a regular box initially; however, be prepared to "grow your litter boxes" as your cat matures. Cats need space to perform the digging and olfactory rituals involved in the elimination process. Have you ever paid attention to what your cat does in the litter box? Cats go in, sniff, scratch, sniff, move around, maybe turn and continue on until they have "just the right place" and then eliminate. Afterward, they go through much the same process in order to cover their waste (Granted, some cats don't cover. Cats cover their waste because, as prey animals, it is smart to "leave no trace behind!").
Location, location, location...isn't that what realtors proclaim? We know they are right! For cats, location of all of their resources is important, litter boxes included. We must understand that when cats eliminate (remember they are prey animals as well as predators), they feel very vulnerable, and truly, they are. Litter boxes should be located in quiet, but not isolated locations. The litter box should have a clear view around it so kitty can see what might approach. It should be in a well lit area, and not hidden behind corners of any kind (this vulnerability is another good reason not to have a covered litter box). Placing a litter box near an appliance is not advisable. Being startled by an appliance while eliminating could drive kitty to find a more secure location.
Following is some advice regarding cleanliness of litter boxes. If using a non-clumping clay litter, it is necessary to remove the solid wastes once or twice daily. As for urine, have sufficient litter (1 1/2 to 2 inches) in the box to stir the litter around so that wet areas mix with the dry to ensure absorption and drying. To keep the litter at its freshest, it's best to mix the wet and dry litter each time you see new urine in the box. Once weekly all litter should be thrown out, the box washed with a gentle (and fairly unscented - floral and other scents can drive kitty away.) cleaner, such as Dawn or Soft Scrub Gel, and fresh litter placed into the box.
When I first started using clumping litter, there were no instructions regarding how to be rid of the waste once clumped. Until recently (Litter Genie), there was no product sold in which to put the waste and discard it. Initially, I did what others have done and used plastic grocery bags. Over time, I switched to using Freezer Zip Lock bags. They hold in the odor and there's not much worry of them puncturing. Litter boxes should be scooped at least once daily, preferably twice or more to keep the litter clean and your cat happy. The small, broken pieces should be removed as well as large clumps. Doing so lessens the amount of bacteria and odor build up and provides clean space for your cat to perform their elimination activities. As the litter is used, add fresh litter to keep the level at 1 1/2 to 2 inches of depth. Following this regimen should keep the litter fresh so that it can be used for approximately four weeks. At that point, if not before, all litter must be thrown out, the box washed with a gentle (no odor) cleaner, as stated above, and new litter placed in the box.
These guidelines will help cat parents set their kitty up for litter box success! So just remember, a large litter box, a litter your kitty will like, a safe location and keep it clean!
Should you be experiencing litter box issues, refer to the Behavior/Litter box link on this site.