Because waste is promptly removed and contained in the base, typical litter box odours will be significantly reduced with Litter-Robot. Litter-Robot 4 features an optional OdorTrap® System designed to neutralize litter box odours. This system uses the combination of a sealed waste drawer and carbon filter to reduce odours. You can opt to replace the carbon filter with OdorTrap® Packs to eliminate litter box odours through natural chemistry. For Litter-Robot 3, a large carbon filter located in the front of the waste drawer absorbs odours and moisture to discourage mold growth (a major culprit of that telltale litter box smell). The amount of odour control Litter-Robot will provide depends on the amount of odour created—by how many cats use it, what type of litter you use, and your cats’ diets, among other things. Of course, the more often you empty the waste drawer, the less opportunity there is for odour to escape. That said, if you empty the waste drawer and notice Litter-Robot is still a source of unpleasant odours, we recommend changing out the bed of litter completely, deep-cleaning Litter-Robot at least once every 3 months, and replacing the carbon filter as needed. It is also worth noting that scented litters are generally not as effective at absorbing odours as unscented litter. Instead, we recommend an unscented, odour-trapping, natural litter.