Do self-cleaning litter boxes smell?

Where the smell comes from

The ASPCA notes that urine contains ammonia. It warns against cleaning accidents with an ammonia-based product, because the smell may draw the cat back to the same spot.³

Cornell Feline Health Center also advises against cleaners with ammonia or vinegar, because their smell is close to urine and they may irritate the cat.⁴

PetSafe describes its crystal litter as absorbing urine and drying solid waste to remove odors. It also says the crystal litter does not clump.²

Odor parts the manuals describe

Litter-Robot 4: a flexible carbon filter pad sits on the outer bottom of the Globe, directly over the Waste Drawer, to absorb odors. Whisker says one filter should last about 1 month under normal use, and that the unit still works without the filter.¹

Litter-Robot 4: brush-type seal strips on the top and bottom of the Base help contain odors within the Waste Drawer. The manual says to replace them when they are worn flat or peeling up, and to keep them dry when cleaning the Base.¹

PetSafe ScoopFree: solid waste is raked into a waste trap with a lid. The manual says the optional privacy cover helps block odors.²

PETKIT Pura Max: the parts list includes an Odor Eliminator N50, which the manual says is not included in some versions. A separate PETKIT Air Purifier Smart Spray, sold separately, can be linked in the app to run odor removal after the cat uses the box.⁵

The table below shows the waste bin size for each model in our database, where the maker states one.

Emptying the waste

Whisker says to empty the Waste Drawer when the light bar flashes blue. It says twice a week is typical for two average-sized cats, and once a week is usually enough for one cat.¹

PetSafe says to change the disposable litter tray when the crystals are saturated (most of the litter turns yellow) or when the waste trap is full and its cover will not close completely.²

PetSafe also says the ScoopFree was designed for one or two cats, and for homes with more cats it recommends one box for each two cats, at a minimum.²

Litter type and depth

Each box is built for a certain litter. The ScoopFree manual says to use only PetSafe crystal litter trays and no clay, natural or other crystal litter. The Litter-Robot 4 manual lists litters that do not work, including non-clumping, pine-based and newspaper-based litters.¹²

Whisker says to fill the Globe up to the raised MAX Fill Line without overfilling, and to check the level each time you empty the drawer.¹

For ordinary boxes, Cornell says most cats like a fine, unscented litter, one to two inches deep. A self-cleaning box should be filled to the line its own manual shows.⁴¹

Washing the drum, globe and drawer

Whisker suggests washing out the Globe every one to three months. The Globe can be washed with water and mild soap and must dry completely before you put it back. The Waste Drawer can be cleaned with soap and water. The Base must never be submerged, sprayed or soaked.¹

PETKIT says to wash the cylinder and litter sifter with a moderate amount of detergent and rinse them well. The main unit should only be wiped, never rinsed or put in water, and parts go back only when completely dry.⁵

PetSafe says not to use bleach or chemicals on the rake; wipe it with a sponge or soft brush.²

When a change may be a health sign

Signs of a lower urinary tract problem include straining or pain when urinating, urinating more often, blood in the urine, and urinating outside the box.¹⁰¹¹

A cat that cannot pass urine is an emergency and needs a vet right away.¹⁰¹¹

Kidney disease, thyroid disease and diabetes can change a cat's litter box habits.⁴¹²

The first step when a cat goes outside the box is a vet check for medical problems.³⁴

Many cats take to a self-cleaning box without trouble, but some avoid it.³¹²

Checklist

• Empty the waste drawer when the box signals it is full. For a Litter-Robot 4, Whisker gives once a week for one cat and twice a week for two.¹
• On a ScoopFree, change the tray when most crystals are yellow or the waste trap lid will not close.²
• Replace the Litter-Robot 4 carbon filter as needed; Whisker says about 1 month under normal use.¹
• Replace Litter-Robot seal strips when they are worn flat or peeling.¹
• Use only the litter type your manual allows, and fill to the marked line, not above it.¹²
• Wash the globe or drum with mild soap or detergent, let it dry fully, and never soak the base.¹⁵
• Do not clean with ammonia-based products.³⁴
• Call your vet if your cat strains, urinates more often, has blood in the urine or goes outside the box.¹⁰¹¹