Most kittens or cats will instinctively learn to use a litter tray. Training a human to provide a clean and suitable litter tray is more difficult
Most kittens will learn to use a litter tray as soon as they are mobile, usually by copying mum, but also because a litter tray is simply a good place of choice for a cat to do its business. You can easily show a cat or kitten where to do its toileting by simply placing it in the litter tray after feeding (this is often when cats go to the toilet) and giving it gentle praise after it has done its toileting. This action just about sums up the amount of training you need to give your cat to use a litter tray, the rest of the training is for the human to ensure that the cat continues to want to use the litter tray.
Litter tray location
Cats do not like being watched or disturbed when toileting, so a location which is as quiet and discrete as possible is best. Usually a very little used corner, under the stairs, or a utility room are best. The tray should be easy to access from at least three sides - cats often stand by the side of the tray to dig and cover their waste. Avoid areas where the cat is likely to be interrupted suddenly, such as a doorway or busy walkway.
Litter tray cleaning
Cats do not like to use a dirty litter tray so it is important to clean it regularly, ideally twice a day but at least once a day at the very minimum. A basic clean involves removing any soiled litter and clumps and topping up with new litter. You will also need to give the tray a complete clean twice a week - throw away all the litter, clean the tray with hot water, use a pet disinfectant, dry it and refill with fresh litter. If your cat does its toileting around the house, one of the first things to check is that your litter tray cleaning routine is sufficient.
Litter trays need daily cleaning, or your cat may look elsewhere
What if a trained cat toilets outside the litter tray?
Sometimes called 'protesting', a trained cat can change its behaviour in 'protest' of any new situations it is not happy with, or changes in routine. If your cat starts toileting outside of the litter tray, first check all of the following:
Is the litter tray in the right place
Is the litter tray clean
Has the litter type been changed
Has there been a change in daily routine of the owners
Is there a new addition to the household
Has the environment been changed (i.e. redecorating)
Don't punish your cat!
An often heard piece of advice is that if your cat does its toileting on the floor, rub its nose in it to stop it from doing it again. This is completely wrong and all it will do is make your cat wary of you. Shouting, nose rubbing, or any form of punishment will simply not be recognised by your cat as an instruction not to toilet on the floor.
Toileting around the house - a sign of health problems?
There are a number of health issues, such as urinary or bladder infections, which can cause your cat to toilet outside of the litter tray. The main reasons for the effect are that either the health issue is causing your cat to need to toilet urgently without much warning, or there is discomfort when toileting and this has been associated with the litter tray. If you have gone through all the possible problems above, it would be best to take your cat to the vets for a checkup.
Solving a problem case
Sometimes a cat will toilet around the house even when all the above concerns are addressed. In these cases some time needs to be dedicated to getting the cat back to using litter trays. If your cat is toileting in a particular area of the house, then placing something in that area such as some furniture, food bowls, or even just some plastic sheet, will change its purpose. If your cat has a preference of material to toilet on, such as carpet, wood, or newspaper, it may be worth trying to put some of the same material inside the litter tray. If your cat sometimes toilets outside, try putting some soil or lawn inside the litter tray. All these methods are designed to change the cats perception of where it should go to the toilet. Make the places it goes in the house undesirable locations, and make the litter tray a desirable location.