Flushable or Compostable

Flushable * Compostable

Before we dig too deep into the different litter options it’s important to talk about the flushable or compostable claims on cat litters. These claims mostly apply to non-clay litters. Whether a litter type is flushable or compostable will be listed as an advantage further down on this page. Please keep in mind the “advantage” may not be as good as it seems.


Flushable cat litter seems convenient, especially if you don’t have easy access to your outdoor trash receptacle, but there are a lot of problems with flushing litter away.

  • Most flushable litters are not septic-safe
  • Water-saving toilets often don’t do a great job handling litter
  • If your litter clumps you need to break up the clumps before flushing
    • You don’t want to break them up inside the litter box, because that will leave dirty litter behind
  • All flushable litter has the potential to clog pipes
  • Cat poop is often very dry and can stick in pipes in unexpected ways, increasing the risk of clogs
  • Most municipal water treatment plants are not set up to handle the pathogens common to cat feces (such as toxoplasma gondii), allowing them to enter waterways and possibly spreading illness to humans and other animals
    • In some areas it is illegal to flush cat litter, and if damage of city infrastructure is traced back to your home you could be on the hook for thousands (or even millions) of dollars worth of damage
  • Flushing litter can use a significant amount of water, which is especially problematic if you’re in a low water or drought area
  • If you are flushing litter from multiple cats you increase your water use and your risk of plumbing problems


Nearly all biodegradable cat litters list something on their packaging about being compostable. While it is technically true that they can be composted there are some things to consider before attempting to compost cat litter.

  • Compost made from cat litter should never, ever, under any circumstances be used with food producing plants or trees, unless you want to risk infecting anyone who eats from those plants with toxoplasmosa gondii or other possible pathogens
    • The compost pile would need to reach temperatures of 165F (73C) to kill off toxoplasmosa gondii
    • There are commercial enzymes available that may help with the breakdown of these pathogens
  • Used litter doesn’t make a good quality compost for gardening purposes. It’s usually too high in nitrogen can burn or kill plants
  • Chemicals from any added fragrance in litter often does not break down in the composting process and can degrade your soil
  • In many areas it is illegal to have pet waste accumulating in your yard
    • Bin composting vs. pile composting may allow you to compost in these areas, but be sure to check the regulations first.