Cleaning the litter tray is nobody’s favourite job, which is exactly why it drifts. You scoop when you remember, top it up when it looks low, and change the lot once the smell finally forces your hand. The problem is that your cat’s nose is vastly more sensitive than yours, so a tray you consider perfectly acceptable can already be unpleasant enough to put them off using it.
Getting the timing right is not complicated and takes about five minutes a day. Here is the routine UK cat welfare charities and vets actually recommend, how it shifts depending on the litter you use, and the warning signs that mean something more than housekeeping is going on.
Quick answer: how often to change cat litter
Scoop your cat’s litter tray at least once a day, and ideally twice, removing every clump and every solid. Do a full change, emptying the tray and washing it with hot water and unscented detergent, at least once a week if you use non-clumping litter. With clumping litter that is scooped properly every day, a full change every one to four weeks is usually enough. Change sooner if the tray smells, if more than one cat shares it, or if your cat starts hesitating before stepping in.
Cats Protection advises removing waste twice daily and washing the tray weekly, while International Cat Care notes that well maintained clumping litter can stretch to two to four weeks between full changes. Both agree on the part that matters most: daily scooping is not optional.
The three cleaning jobs people tend to muddle up
“Changing the litter” actually covers three separate tasks. Mixing them up is why so many trays end up either neglected for weeks or emptied wastefully every other day.
1. Scooping, every single day
Scooping means lifting out solid waste and urine clumps and binning them. Do it at least once daily, preferably morning and evening. This is the highest impact habit you have, because the sharp ammonia smell comes from urine sitting in the litter rather than from the litter itself. Remove the source and the odour largely disappears.
2. Topping up, as needed
Every scoop takes a little litter with it, so the depth drops over time. Add fresh litter to bring it back to roughly 3cm, the depth research suggests most cats prefer: deep enough to dig and cover, shallow enough to feel stable underfoot. Topping up keeps the tray usable between full changes, but it is not a replacement for one.
3. The full change and tray wash
This is when the tray is emptied completely, scrubbed, dried and refilled. It removes the film of urine residue and bacteria that clings to the plastic and causes that stale, lingering smell even after fresh litter goes in. If a tray still smells once it has been refilled, it needs washing, not more litter.
How often to change cat litter, by litter type
The litter you use genuinely changes the schedule, because clumping and non-clumping litters handle urine in completely different ways. Clumping litter traps urine in a solid ball you can lift straight out. Non-clumping litter absorbs urine and holds it in the tray until the whole lot is replaced.
| Litter type | Scoop | Full change (one cat) | Worth knowing |
|---|---|---|---|
| Clumping clay (bentonite) | Twice daily | Every 2 to 4 weeks | Only lasts this long if clumps come out daily. Can be dusty. |
| Non-clumping clay | Daily | Weekly | Urine stays in the tray, so odour builds noticeably faster. |
| Wood pellets | Daily, plus sift sawdust | Every 1 to 2 weeks | Came out best in the RSPCA’s own litter trials. Low dust, good value. |
| Paper pellets | Daily | Weekly | Soft and often recommended after surgery. Saturates quickly. |
| Silica crystals | Solids daily, stir the rest | Every 2 to 4 weeks | Strong odour control, but crystals stop absorbing once saturated. |
| Tofu and other plant-based | Twice daily | Every 2 to 3 weeks | Biodegradable, lightweight and clumps firmly. |
| Corn or wheat | Twice daily | Every 2 to 3 weeks | Natural clumping. Store somewhere dry to avoid mould. |
If you are weighing up a switch, our guide to tofu cat litter in the UK compares plant-based litters on clumping strength, dust and running cost.
How many litter trays does your cat need?
The standard UK welfare guidance is one tray per cat, plus one spare. A one-cat household should have two trays; two cats should have three. It sounds excessive until you realise many cats prefer to urinate and defecate in different places, and that a spare tray gives you a margin of error on the days life gets in the way.
Cats Protection also advises against lining trays up in a row, because a row reads to a cat as one large toilet rather than several options. Spread them out, including upstairs and downstairs if you have more than one floor.
Where you put the tray changes how often you will clean it
- Away from food and water bowls. Cats will not happily eat beside their toilet, and a tray placed next to a water bowl can put them off drinking. If you already suspect your cat is not drinking enough water, tray placement is worth checking.
- Somewhere quiet. Washing machines, tumble dryers, boilers and busy doorways all make a tray feel unsafe to use.
- Not beside the cat flap or a full-length window. A cat who feels watched, whether by a neighbouring cat or by the household, tends to rush or avoid the tray.
- On a washable surface. A double-layer litter mat catches tracked granules and saves you sweeping the hallway twice a day.
A badly placed tray often gets used hurriedly and incompletely, which owners then misread as the tray not needing changing often. The litter is fine; the location is not.
How often to change cat litter with two or more cats
Multiple cats do not simply double the workload, they compress the timetable. A tray shared by two cats needs scooping at least twice daily and a full change roughly twice as often as the single-cat guidance above: weekly for clumping litter, and every three or four days for non-clumping.
Watch, too, for the more timid cat quietly avoiding a shared tray. Sudden accidents in a multi-cat home are far more often a resource problem than a training problem, and adding a tray in a different room frequently solves it on its own. Lowering general household tension helps as well, and our cat enrichment ideas for indoor cats cover practical ways to give each cat space of their own.
Kittens, senior cats and cats who are unwell
- Kittens use the tray more often relative to their size and are still learning, so scoop more frequently and choose a low-sided tray they can climb into easily. Many vets advise against clumping litter for very young kittens who may try to eat it.
- Senior cats are often stiff or arthritic. A larger tray with a low entry point, and a shorter walk to reach it, matters far more than the brand of litter. An older cat who suddenly starts missing the tray may simply be finding it painful to climb in.
- Cats recovering from surgery are usually sent home with paper-based litter because it does not stick to wounds. Follow your vet’s instruction here rather than the general schedule.
- Cats with kidney disease or diabetes produce considerably more urine, so their trays saturate much faster. A clear increase in the size or number of urine clumps is worth mentioning to your vet.
- Long-haired cats carry litter in their coat and between their toes. Regular grooming at home cuts the mess dramatically and gives you an early look at any soiling around the rear end.
What happens if you do not change cat litter often enough?
The consequences are practical rather than dramatic, but they stack up quickly.
- Your cat toilets elsewhere. Carpets, bath mats and laundry piles are the usual substitutes, and once a cat has soiled a spot they tend to go back to it.
- Ammonia builds up in the room. Urine breaking down releases ammonia, which is unpleasant for you and irritating to feline airways in a small, enclosed space.
- Parasites survive longer. Roundworm eggs and toxoplasma in cat faeces need time in the tray before they become infectious, which is precisely why removing waste daily matters.
- Health problems go unnoticed. The tray is the best early warning system you have for urinary and digestive illness. If you cannot see what your cat is producing, you cannot spot the moment it changes.
How to clean a litter tray safely
- Tip the used litter into a sealed bag and put it in your general waste bin. Most UK councils do not accept cat litter in food or garden waste collections, including the compostable types.
- Wash the tray with hot water and a plain, unscented washing-up liquid or biological detergent.
- Rinse thoroughly. Cleaning residue is more likely to put a cat off the tray than a little dirt is.
- Dry the tray completely before refilling, because damp trays cause litter to stick and smell faster.
- Refill to roughly 3cm.
- Wash your hands properly afterwards.
Some household disinfectants are genuinely dangerous to cats. International Cat Care warns that disinfectants containing chloroxylenol, the type that turns cloudy or milky when added to water, are toxic to cats. Avoid phenol-based cleaners and anything heavily perfumed with pine or citrus. Hot water and plain detergent is both safer and perfectly effective.
Common litter tray mistakes cat owners make
- Pouring fresh litter over a soiled tray. It masks the smell for a day and leaves the residue sitting underneath.
- Choosing scented litter or scented cleaners. A perfume you find pleasant can be overwhelming to a cat, and both charities advise against it.
- Filling the tray too deep. More litter is not better. Around 3cm is the sweet spot.
- Using plastic liners or newspaper underneath. Cats often catch their claws in liners and dislike the sound, and the liners tear anyway.
- Buying a tray that is too small. As a rule of thumb, a tray should be about one and a half times your cat’s length from nose to base of tail.
- Switching litter type overnight. Introduce a new litter gradually across about a week, or offer it in a separate tray alongside the old one.
- Cleaning the tray the second your cat steps out of it. Give them a little privacy and a few minutes.
When it is not a cleaning problem: signs to ring your vet
A litter tray tells you a great deal about your cat’s health. Contact your vet promptly if you notice any of the following.
- Repeated trips to the tray producing little or no urine
- Straining, as though constipated, or crying out while toileting
- Blood in the urine or faeces
- Excessive licking around the rear end
- A sudden change in the volume, frequency or smell of urine
- Diarrhoea lasting more than 24 hours, or any diarrhoea in a kitten
A cat who cannot pass urine is a medical emergency. The PDSA describes a blocked bladder as life-threatening if left untreated, and notes it is most common in male, neutered, overweight or stressed cats and those fed a dry diet. Do not wait overnight to see whether it settles.
If a same-day vet trip is needed, our calm, step-by-step guide to getting a cat into a carrier without the stress can save you valuable minutes. This article is general information and does not replace veterinary advice: your vet knows your cat.
Frequently asked questions
Can you put fresh litter on top of old litter?
Topping up between full changes is fine and expected, provided you have removed the clumps and solids first. What does not work is pouring clean litter over a soiled tray to hide the smell. The urine residue stays in the litter and in the plastic, and the odour returns within a day.
How long can cat poo be left in the litter tray?
As little time as possible, and certainly no more than 24 hours. Faeces should come out at every scoop. Beyond roughly a day, parasite eggs present in cat faeces can become infectious, and most cats start avoiding a tray with waste sitting in it well before that point.
How often should you change cat litter for two cats?
Ideally you would run three trays for two cats, which spreads the load and reduces conflict. If two cats share a single tray, scoop at least twice daily and do a full change about twice as often as for one cat: weekly for clumping litter, and every three to four days for non-clumping.
Do covered litter trays need changing more often?
In practice, yes. A hood traps odour inside, which is pleasant for you and considerably less so for the cat using it. Cats Protection suggests hooded trays may need washing roughly twice a week. Covered trays suit some cats very well, particularly nervous ones who like privacy, but they need a stricter schedule and enough room for a larger cat to turn around comfortably.
How often should wood pellet litter be changed?
Remove solids daily and sift out the sawdust that forms as the pellets break down, usually every couple of days. A complete change every one to two weeks suits most single-cat households. The RSPCA has reported that wood-based pellets performed best in its own litter trials.
Is it safe to empty a cat litter tray when pregnant?
NHS guidance advises avoiding emptying litter trays during pregnancy where possible, and asking someone else to take the job on. If that is not an option, wear disposable gloves, clean the tray daily and wash your hands thoroughly afterwards. Daily cleaning matters here because toxoplasma in cat faeces needs time in the tray before it becomes infectious.
Why does the tray still smell of ammonia after I change it?
Ammonia comes from urine breaking down, and the residue gradually soaks into the plastic. If the smell survives a full change, wash the tray properly with hot water and unscented detergent and dry it completely. A tray that is heavily scratched or more than a couple of years old holds residue in the scratches and is worth replacing.
Key takeaways
- Scoop daily, ideally twice. No other habit makes as much difference.
- Full change and tray wash at least weekly for non-clumping litter, every one to four weeks for clumping.
- Keep litter around 3cm deep and top up after scooping.
- Provide one tray per cat plus one spare, placed apart and away from food and water.
- Clean with hot water and unscented detergent. Avoid chloroxylenol and phenol-based disinfectants, which are toxic to cats.
- Multi-cat homes, kittens, senior cats and cats with kidney disease all need a faster schedule.
- Straining, frequent unproductive trips or blood in the urine mean a vet call, not a change of cleaning routine.
A cleaner tray, a happier cat
Get the daily scoop right and everything else falls into place. A tray your cat is genuinely happy to use is quieter, cleaner and a great deal cheaper than replacing a rug, and it hands you a daily health check you would otherwise never get.
If you are refreshing your setup, our cat litter and housetraining range includes large enclosed litter trays for cats who prefer their privacy, along with mats that catch tracked granules before they reach the hallway.
