Cover material is one of the unsung heroes of a successful composting toilet setup. The right cover helps manage moisture, control odors, and keep your solids bin clean. In this article, we’ll walk through what makes a good cover, creative ways to source it, and a few tips from our own team’s off-grid experience.
In this article
- Why use cover material?
- What makes a good composting toilet cover material?
- Coverings
- Peat Moss
- Coconut coir
- Sawdust
- Paper and cardboard
- Yard waste
- Feed waste
Why Use Cover Material?
Think of your cover material as the “secret sauce” that keeps a composting toilet happy. A fluffy layer of clean, organic matter immediately blankets new deposits, blocking sights and smells before they start. Because these fibers soak up excess moisture, they eliminate smells that can occur in damp conditions. And since most human waste is nitrogen-rich, each handful of carbon-laden cover balances the mix so when it’s time to empty the bin, your solids are compost-ready, no extra materials needed.
Not sure how to get started with off-grid waste management? Our Beginner’s Guide to Compost walks you through various composting methods and our FREE compost toilet build plans will give you a budget friendly way to build your first compost toilet.
What Makes a Good Cover Material?
A good cover material:
- Is carbon-based
- Has relatively fine particles to block odors and flies
- Does not inhibit the microbial action needed for composting (though this is less important if you won’t be composting the contents of your toilet)
For example, wood chips are not ideal since the pieces are large, requiring you to use a lot of extra material to prevent odors and flies, which causes the receptacle to fill up too fast. Lime should not be used, since it interferes with microbial action, which prevents composting. And while wood ashes can be used occasionally for reducing smell, it harms the microbes, making it not ideal for composting. However, there are a number of inexpensive and sustainable options that we’ll go over here.
Peat Moss
Peat moss is a common material used by folks in their compost toilet. It’s fairly easy to source and is affordable. However, peat moss isn’t a sustainable material and is quite harmful to the environment. Peat moss is mined from sphagnum peat bogs that take hundreds or thousands of years to form. Mining these wetlands can damage them in ways that are difficult to recover from.
Hot Tip: Did you know you don’t need to rely on pricey peat moss for your composting toilet? There are free or low-cost alternatives that work just as well, or even better. Keep reading to find out what they are!
Coco coir
Made from the shredded hulls of coconuts, which is a waste material from processing coconuts for food, coconut coir is sustainable, relatively inexpensive, and readily available. It’s an excellent option for small-scale and nomadic applications since it’s compact, easy to store, and can be purchased in convenient bricks. Look for bricks (approximately the size of masonry bricks) at hardware stores or nurseries sold as seed starters. Add some water to hydrate them a bit for best performance.
- Made from coconut husks
- Sustainable, compact, and easy to store
- Sold in brick form at hardware stores and nurseries
- Just add water to fluff before use
- Ideal for RVs, vans, and tiny spaces
Sawdust
You may be able to acquire sawdust or small wood chips or shavings for free at a local saw mill or wood shop if there is one in your area. If you live in a wooded area and are breaking down your own firewood, the sawdust and small wood chips you produce is an ideal material for using as a cover material. Just make sure the sawdust has been milled into small pieces. As with other cover materials, you want the sawdust to have a bit of moisture for the best odor-blocking but not be sopping wet.
- Often free from local sawmills or woodshops
- Can also come from splitting your own firewood
- Works best when milled into fine pieces
- Slight moisture helps with odor control — not too wet
- Natural, effective, and easy to source in wooded areas
Paper or Cardboard
Waste paper or cardboard (even junk mail) can be used, but it should be ground up as fine as possible for use as a cover material. Make sure you use paper with no plastic or laminate liners, and without ink (soy-based ink is fine).
If you don’t have a paper shredder available, you can soak paper for a few days and use a drill with a paint mixer attachment to turn paper into pulp. Let dry and you’ll have plenty of cover material to use.
- Use non-glossy, ink-free paper (soy ink is okay)
- Must be shredded or pulped for best coverage
- Soak and blend if no shredder is available
- Avoid plastic-lined or laminated materials
- A great way to reuse junk mail and cardboard
Yard Waste
Yard waste is a free and easy cover material for your composting toilet. This can include grass clippings, crumbled leaves, or pine needles. Yard waste needs to have the right texture to be an ideal cover material, so dried materials that crumble easily are best. If yard waste materials are too large to use directly in the solids bin in your toilet, they can still make a great cover for your compost pile.
- Includes leaves, grass clippings, and pine needles
- Best when dry and crumbly for good coverage
- Free and abundant in most seasons
- Larger pieces can be used on the compost pile instead
Feed Waste
Feed waste can include grain chaff, rice hulls, coffee grounds, and spent grain. If you live in a farming area, check with your local grain mill or feed store to see if you can obtain grain chaff for cheap or free. In areas where rice is a local staple, rice hulls can be obtained in a similar fashion. While a single household probably won’t produce enough coffee grounds for use as a cover material, your local coffee shop might be willing to set them aside for you. Spent grain, a waste material from your local brewery or distillery, could also be used as a cover material, but might cause your bin to fill up faster than a lighter weight material. If using coffee grounds or spent grain, be sure to partially dry them out before use.
- Includes grain chaff, rice hulls, coffee grounds, and spent grain
- Often free from farms, feed stores, coffee shops, or breweries
- Dry before use to prevent odors and excess moisture
- Heavier materials like spent grain may fill the bin faster
Conclusion
The right cover material can make or break your composting toilet experience—and thankfully, you don’t need to spend a fortune to find a great one. From sawdust to spent grain, there are plenty of sustainable, affordable options that do the job well and prep your solids for the compost pile. Whether you’re building your first system or fine-tuning an existing setup, experimenting with different cover materials is part of the fun. Want help getting started? Grab our free compost toilet build plans or check out our Beginner’s Guide to Compost for more tips from the field.
| Material | Performance | Cost | Availability | Scent |
|---|---|---|---|---|
| Coconut Coir | Excellent | $$ | Online | Neutral |
| Wood Shavings | Great | Free–$ | Local Shops | Pleasant |
| Hemp Bedding | Excellent | $$$ | Pet Stores | Mild |
| Pine Pellets | Good | $–$$ | Hardware Stores | Fresh Pine |
| Shredded Leaves | Seasonal | Free | Backyard | Earthy |
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