It’s every cat owner’s Holy Grail: an odorless litter box.
Most cats, unlike most dogs, eliminate in the house and so the struggle for cat owners seeking to see, but not smell, their cats is real.
There’s a whole industry devoted to reducing the odor of the cat box, and plenty of products that claim to eliminate it completely. There is litter made of old-fashioned clay, of course, but also newsprint, pine wood, and walnut shells. There is litter made of wheat, corn, and crystals, and micro pearls and ultra pearls – whatever they are. There is clumping and non-clumping styles, and scented and unscented and even lightly scented litters, and litters that advertise themselves as lightweight. There is also a whole category of litters that contain weird ingredients in the name of controlling odor, like probiotics or green tea.
There are litter-box “systems,” which employ pee pads to absorb urine and lock in the smell. And there are robots that will sift through the litter for you when it senses a cat has used the box, to prevent waste from sitting out too long. And finally, there are Diaper Genie-style trash cans for the manual scoopers who want the smell of cat waste to be locked away the moment a box has been scooped.
Do any of these crazy litter-box products and systems really work?
Read the reviews and you find equally vigorous champions and detractors for nearly every product on the market. Maybe certain products work for some cats or some households. Maybe some individual cat owners have a keener sense of smell than others, or a greater or lesser tolerance for the odor.
The truth is, there is only one thing that is truly effective in keeping litter-box odor under control: cleaning.
Why you must keep your cat litter box clean
Regarding litter box odor, you’re not the only one who finds it unpleasant. Fail to keep the box clean and your cat may protest by refusing to use it. This is not a habit you want your cat to establish. Keep it smelling fresh, and you and your cat will be happier for it.
Is it possible to eliminate the smell of the cat box completely?
Nothing will completely eliminate litter-box odor, especially if you have a keen sense of smell. The only time the litter box will smell completely fresh is the moment between a thorough cleaning and the next time your cat needs to use it.
That being said, litter-box odor can be very well managed with diligence. Clean, clean, clean, clean. Scoop urine-soaked litter and solids at least twice a day. Scooping frequency is the most important factor in controlling odor. By removing the liquids and the solids in the pan, you're removing the source of the odor.
You're also keeping your cat happily using the pan. The only thing that can smell worse than a dirty litter box is the smell when a cat starts refusing to use the litter box.
What is the best way to scoop a litter box to reduce odor?
Clumping litter makes it easier to remove wet litter, but even if you prefer a non-clumping product, scoop out the wet mess with a solid spoon or shovel.
Every time you scoop, you need to replenish what you've removed from the box. Sprinkle some fresh litter into the pan every time you take some litter out.
Don't raise the overall depth of the litter as cats prefer their litter to be a bit shallower than you might think. Two to 3 inches of litter is perfect. I sometimes mark litter height with a Sharpie at the corner of the pan to remind myself what 2-3 inches from the bottom looks like. It's easy to add too much litter.
It's not that fresh litter itself controls the odor; it's just that it provides the right amount of material for the cat to use when covering her own urine and feces. Covered waste has less odor than uncovered waste.
Clean the litter pan, too
Washing the litter box on a regular schedule is not only essential for your pet's health and safety but for controlling odor. Cat feces and urine can build up on the sides and bottom of the pan and must be removed. Thoroughly washing and then disinfecting with a bleach solution physically removes waste and kills bacteria, keeping smells and illness-causing microbes to a minimum.
Completely dump and wash the box once a week. You might be able to get away with washing every other week if you’re using a clumping product. Wash the box and the scoop with dish detergent and spray or submerge both in a mild bleach solution (add about ¾ cup of bleach to a gallon of water). Air or towel dry. Then add 2 or 3 inches of cat litter.
An important note: be sure to completely rinse your litter box before applying the bleach solution. Urine contains ammonia. Mixing bleach and ammonia can cause the formation of chloramine gases, which are toxic.
Does the type of litter box matter?
Get the largest box you can stand having in your house. Some people use a large plastic storage container with a side cut down to allow the cat to enter.
Why is bigger better? For one thing, it gives your cat a fresh place to step every time he enters the box. Cats are fastidious creatures and they want a clean spot to toilet. Litter box "fails" are much less likely to occur if you keep your cat happily using the box. The more litter there is to absorb liquids and cover solids (while still sticking to the 2-3-inch depth rule) the more likely odors will be kept under control.
Should I use a deodorizer?
Deodorizers are tricky. Some merely mask the smell of waste with perfume and the scent tends to dissipate rather quickly, negating any "odor-hiding” benefits. Moreover, cats have a far more sensitive sense of smell than we do and might find the perfume-y smell offensive.
To reiterate: the main goal is making sure that your cat is not discouraged from using the litter box to toilet. You may adore the lavender scent of the new deodorizer you just bought, but the only opinion that matters when it comes to litter deodorizers is your cat’s.
How about unscented deodorizers?
There are as many opinions about unscented deodorizers as there are products on the market.
Some of the "unscented" products still have a smell that some cats and some humans find unacceptable. Moreover, some of these unscented varieties are crystal-based and some cats don't like the feeling of the crystals on their paws.
Another type of unscented deodorizer is powdered-activated charcoal. It does seem to reduce odor as promised, but cats may track the black powder around the house on their paws. (Noooooooo!) There are also charcoal-infused sheets that can be placed underneath the litter, but cats tend to pull up the sheets as they scratch around in the box.
Does the placement of the litter box matter?
No one wants a litter box sitting in the middle of the kitchen, or in the middle of anything for that matter! We like to tuck our litter boxes in the laundry room, or in an unused basement bathroom, and in corner that gets little human foot traffic.
But these are almost always the worst spots for a litter box in terms of odor control. Litter boxes need to be placed where there is air movement to keep odors from stagnating.
Your cat’s preference also needs to be taken into consideration with regard to placement of the litter box. Litter boxes need to be put where the cats like to go. Just because you'd like the box to be in the attic, doesn't mean your cat will be comfortable going there to toilet.
Most cats enjoy well-lit, comfortable (forget the chilly garage!), quiet (that eliminates the laundry room with its loud buzzers), places with constant access (don't choose a bathroom that people use – we tend to close the door!) to toilet.
If you have a multi-cat household, the box needs to be placed where a cat using the litter box can see other cats coming and going.
What about litter-box hoods and trap doors?
Covers or hoods trap odors. That's good for you, but less so for the cat who may not enjoy being trapped inside with the smell.
Some litter-box hoods have a space to hold a charcoal filter, which may help keep odors down for both cat and human.
A small study was conducted that showed that when given a choice between open or hooded litter boxes that most cats didn't have a preference. When particular cats showed a preference for one type or the other, they were evenly divided between the two types. Choose the one your cat wants to use.
Does baking soda work to control litter-box smell?
Baking soda works in your refrigerator and litter box in much the same way: it's a base that neutralizes the higher pH of odors.
The great thing about baking soda is that it's non-toxic and has no real scent. It's also inexpensive! Sprinkle some baking soda on the bottom of your litter box after you've thoroughly cleaned it, and then add the litter. As your cat digs around the box, she'll mix a little baking soda into the litter as she goes. Add a little fresh baking soda every time you scoop, too. It's a safe, easy, economical product to experiment with.
One more thought about litter-box odor
The best and least smelly litter box option is the one that works for your cat. Be sensitive to his preferences and keep him happily using the box. You might prefer a covered box, with a pine-scented litter and a scented deodorizer, all tucked away in a corner of your dank basement, but if your cat starts using a corner of the living room instead to do his business, no one is going to be happy.
 “Disinfecting for Pets: Clorox®.” Clorox, 11 May 2018, www.clorox.com/how-to/disinfecting-sanitizing/disinfecting-with-bleach/disinfecting-pets/.
 Maxwell, Megan, and Josh Miller. “Research Study: Litter Box Preference in Domestic Cats.” AVSAB, 11 June 2015, avsab.org/research-study-litter-box-preference-in-domestic-cats/.