Cats are extremely fastidious creatures and their regular toileting routing is easily upset by perceived changes. So it's no surprise that the most common behaviour problems in cats are related to the litter tray. Fortunately, this can usually be remedied fairly easily.

If your cat is refusing to use the litter tray, go to the vet before you do anything else. A thorough physical examination, including urine, stool, and blood tests, will show if the cause is a medical one.

Where to place litter trays
Assuming there are no medical concerns, the next step is to provide enough litter boxes. You need to have the same number of boxes as you do cats, plus one more for good measure. These can be large, unlined, flat boxes, or, if your cat prefers more privacy, use a hooded one. When given the choice, cats prefer to relieve themselves in clean and open areas. They also may be wary of noises, dampness, an inconvenient litter box location or unpleasant smells. So place the boxes in any suitable areas that your cat frequents - the basement may just be too 'inconvenient'. Keep the trays well away from feeding bowls.

Cleaning
Litter trays need to be cleaned once a day. If you clean them too often, your cat won't know what to use the tray for as you'll have removed the scent. If you change it too little, on the other hand, your cat will be put off and go elsewhere.

Cats that habitually go to the toilet outside the litter box should be gently brought to the box once or twice a day. If they relieve themselves inside it, reward them. You could also try placing the litter tray where your cat keeps going to associate the tray with the toilet. If your cat chooses to go in a very unsociable place, try putting pieces of silver foil down - they don't like the texture on their paws. Or you can try moving feeding bowls nearby, as cats don't like to eat in the bathroom!

You should also clean the area very thoroughly and use a spray whose odour cats find repellent, such as a pheromone-based masking spray that you can get from your vet or pet shop. If your cat chooses to use your bathroom as a toilet, just restrict entry by keeping the door shut.

Finally, once your cat has become used to a certain type of litter, try and stick with the same one. Swapping varieties can be very unsettling.