The number and location of the litter boxes are very important issues. Many cats will not use a litter box if it has been used by another cat. In addition, some cats prefer to urinate in one box and defecate in another. Also, a common cause of inappropriate elimination stems from a more dominant cat blocking the pathway to the litter box. The more passive/timid cat is forced to look elsewhere for a bathroom. In this situation it is critical to have enough boxes in ‘safe’ areas to minimize the potential for problems.
Don't put all of the litter boxes in the same spot if you have a bully cat that may be blocking a timid cat from the box. Place the boxes in quiet, low traffic areas. The laundry room and other high traffic areas are often not a suitable place due to the noise and may lead to many litter box aversion cases. Also, it is best to not place litter boxes near the cat’s eating area.
Newly adopted kitten or cat, keep their world small (a single room) until you know that they are using the litter box and is comfortable in his room. Be sure this room is a room that you and the household will visit. Depending on the kitten or cat, this may take several days or a couple of weeks. Only when he is comfortable in one room should you open up the door and let him venture out. Do not carry him to another part of the house. Instead, let him pick his own path so that he will know how to get back to his litter box.
Even if a new kitten is brave and sociable, please do not just turn your kitten loose in a large area please do not expect him to know or remember that his bathroom is 'down the hall...second door on the right'. When a kitten has to go....they can only hold for a short amount of time. Two boxes can help in this situation and it is recommended that you have at least two at any age.
Good Rule of thumb is have one more litter box than cats...3 cats you should have 4 boxes.