How to Compost Cat Litter

Composting cat litter is the most environmentally friendly way to dispose of the litter as it reduces the amount of waste we send to landfill and creates a rich organic material to add to our gardens. Composting litter though is not as simple as composting food scraps, so having some knowledge will help you understand any risks.

Can You Compost any type of Cat Litter?

Some types of cat litter can be composted. Any biodegradable cat litter that is free of additives can be composted. Plant-based litter containing chemical additives and clay litter cannot be composted. CATMATE is a biodegradable plant-based cat litter that is free of additives and therefore with some knowledge can safely be composted.

But before you begin, it’s important to understand the risks.

You may have heard about the dangers of cat litter to pregnant women and their unborn children. This is because cat faeces can contain any number of pathogens and parasites, including the one we know Toxoplasma gondii. Unfortunately, compost doesn’t often reach the required 75c temperature to kill Toxoplasma gondii. By adding cat waste direct to vegetable gardens, you risk spreading parasites and so this type of compost should only be used for plants/flowers/bushes in the garden and not veggie gardens.

What Types of Litter Can Be Composted?

Any biodegradable, plant-based cat litter with no additives can be composted. This includes CATMATE wood pellet litter, paper, wheat, grass, corn, tofu, and walnut shell litter. Clay and crystal cat litters cannot be composted as they will not break down into organic material.

Composting Litter outdoors and in an area with plenty of space.

Unfortunately, composting cat litter isn’t realistic for everyone so check with your council for restrictions and regulations of disposing cat litter waste.

Tips to safely compost

  • Compost containing cat waste litter should never be used on or near edible plants.
  • If also making compost for an edible garden, avoid cross-contamination between piles.
  • Thoroughly wash hands after handling compost.
  • Composting litter is not recommended for pregnant women or those with a compromised immune system.

How to Compost

Composting requires four main ingredients to be successful. Carbon, nitrogen, oxygen, and water. The key to a healthy compost pile is maintaining a good balance between carbon and nitrogen while allowing the pile an appropriate amount of air and moisture.

To get started with composting you’ll need an area to compost and a shovel or fork to turn the pile. Though not mandatory, a thermometer is helpful. A compost pile on bare earth is ideal. It allows worms and other organisms to aerate the compost pile and move valuable nutrients throughout your lawn and garden.

Alternatively use a compost bin. A digester is a type of compost bin enclosed on the top and sides, but open to the earth on the bottom. Tumblers are fully enclosed compost bins that can be turned to aerate the compost. While either will work, a digester shares many of the same benefits as an unenclosed compost pile.

Carbon-rich matter, or brown material, provides compost with a source of energy. Examples include branches, dried leaves, eggshells, straw, and biodegradable cat litter. Avoid using sawdust or wood chips that have been chemically treated or may contain machine oils. CATMATE has not been chemically treated and is safe to add. Avoid lawn or plant trimmings that have been treated with insecticides or herbicides. Try to avoid using perennial weeds as you may end up spreading seeds.

Nitrogen Sources

Nitrogen-rich matter, or green material, provides compost with the microorganisms needed to oxidize carbon. These include food scraps, fresh lawn clippings, green leaves, used compostable litter.

How to Compost Cat Litter

Composting cat litter is as simple as adding alternating layers of carbon and nitrogen sources while monitoring temperature and moisture. Over time, microorganisms will break down organic waste, like food scraps, leaving behind a nutrient-rich humus that can be used to feed or spread around ornamental garden plants.

Starting Your Compost Pile

  1. Prepare the base of your compost pile. For enclosed bins, start with a 7-8cm layer of topsoil, sawdust, dried leaves, or straw covering the entire bottom of the container. This allows for drainage and improves airflow. For unenclosed compost piles or bottomless compost bins, break/rake up the soil.
  2. Add alternating layers of brown and green materials. Hold off on cat waste initially.
  3. Finally, add your initial batch of cat waste litter. This should be added at the top centre of the compost pile, then completely covered by a layer of brown material.

Adding to the Compost Pile

Once your compost pile is going, it’s best to stockpile brown and green materials instead of adding as you go. This ensures that there’s enough of each to layer effectively. Once you have a sufficient pile of browns and greens, add alternating layers of about 7-8cm. Always top the pile with a layer of brown material. This top layer can be pulled back and reused but is vital to the composting process. If your compost pile begins to get too large, simply repeat the process above and start a second.

Carbon to Nitrogen Ratio

A healthy compost pile has much more brown material than green. Ideally, around thirty parts carbon to each part nitrogen, by weight. Our recommendation is to not overthink the ratio. The reality is that if you add the right materials, with considerably more brown material than green, and allow sufficient oxygen and moisture, you’ll make compost.

Managing Moisture

Your compost heap needs to always stay moist, but never wet. Too little moisture will limit the activity of microorganisms, slowing or stopping the composting process. Excessive moisture can lead to anaerobic conditions and a foul-smelling compost pile. Because temperature is important, water should never be added straight from a hose. Cool tap water can drop the temperature of your pile, disrupting the composting process. Instead, fill a bucket with water and let it warm in sunlight for a day or two before adding.

If you live in a particularly dry climate, you can cover your compost with a piece of rug or carpet, this will help retain moisture while still allowing the pile to breathe. For heavy downpours or in very wet climates, loosely cover the pile with a waterproof tarp.

Oxygen and Airflow

Oxygen can be managed by adding sufficient bulky, brown materials to allow air circulation throughout the pile. Coarse brown materials like dried leaves often allow enough circulation that your pile can breathe, even without turning.

If you’re mostly using less-bulky brown materials, like pellet litter or sawdust, you’ll need to turn your compost pile with a fork or shovel once every few weeks to aerate. But don’t go overboard. It’s possible to turn your compost too often.

The Finished Product

Your compost needs to age until dark and soil-like, smells rich and earthy, crumbles when touched, and the original materials have fully broken down.
How long this takes depends on the size of your compost pile, what materials you’ve used, how well you’ve managed it, and your climate. Typical compost can be ready within three to six months.


Composting biodegradable cat waste is the most eco-friendly way to dispose of litter. It sends less waste to landfills and creates a nutrient-rich humus for lawns and garden plants. If you’re intimidated by the process, you can just bag the waste into biodegradable bag and safely dispose with your waste bin.


Cornell Waste Management Institute. (n.d.). Monitoring Compost Moisture.

Cornell University Powell, E. (2014, November 11). Understanding the Greens and Browns of Compost. University of Florida

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