
How often to change cat litter has two answers, and confusing them is why some boxes smell despite constant work. Scooping is daily. A full litter change and box wash is weekly to fortnightly. Doing the second without the first does not work, and doing the first while skipping the second lets the plastic itself hold odour.
At least once a day, twice for multi-cat homes or an enclosed box. This is a health interval, not a tidiness one: the CDC notes the Toxoplasma parasite does not become infectious until 1–5 days after a cat sheds it in its faeces, so removing waste daily clears it before it matters.
Weekly to fortnightly with clumping litter, depending on how many cats use it. The test is simple — the litter should look and smell dry and clean. If a scooped box still smells the moment you walk past, the remaining litter has absorbed more than it can hold and topping it up will not fix that.
Yes, at every full change. Plastic scratches and holds urine in the scratches, which is the source of smell in boxes that are otherwise scooped diligently. Use unscented soap or a baking soda solution, rinse well, and dry completely before refilling. Never use ammonia-based cleaners — ammonia smells like urine to a cat and invites marking.
No. Adding fresh litter over saturated litter raises the level without removing what is causing the odour, and it steadily increases depth past the one to two inches cats prefer. Top up between full changes to maintain depth, but keep the full change on schedule.
When it smells after washing, or when the surface is visibly scratched or cracked. Most plastic boxes last a year or two of daily use. A box that has started holding odour cannot be reclaimed with cleaning, and cats notice long before people do.

See the covered litter box guide or browse Litter Boxes & Scoops.
Because cats that avoid a dirty box hold urine longer, and holding urine is associated with lower urinary tract problems in cats already prone to them. The cheapest preventive step available to an indoor cat owner is a box clean enough that the cat never hesitates to use it.

Not advisable. Daily is the minimum, and enclosed boxes concentrate odour faster.
No. It masks odour for people and many cats dislike it. Unscented is the safer default.
One to two inches. Deeper does not extend the interval, it just wastes litter.
No. Most litters block drains, and flushing cat waste is discouraged for wastewater reasons.
Yes. They remove clumps; the remaining litter and the unit itself still need periodic replacement and washing.
The litter is saturated or the box plastic has absorbed urine. Do a full change and wash, and replace the box if it persists.
Leave a comment