Boondocking Basics

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How Does a Composting Toilet Work?

How Does a Composting Toilet Work?


A composting toilet stores its contents inside the toilet itself. The storage bin has a layer of natural, absorbent material that starts the composting process. The bin fills up in a couple of weeks, at which point you transfer the contents into a larger composting bin (stored outside) to complete the composting process. How does a compositing toilet work is also dependent on what kind of toilet you have.

how does a composting toilet work
Kildwick Composting Toilet with 12v Fan

How Does a Composting Toilet Work?

Most composting toilets store human waste inside the toilet itself. Many people who use composting toilets typically get about 2-3 weeks of storage before they have to remove the contents.

  • All composting toilets keep two waste bins, one for the poop, and another for the urine. When using a composting toilet, you urinate into the urine bin, and poop in the other. All composting toilets allow you do this in one sitting.
  • The composting process is done only in the poop bin. The urine bin is not used for composting, and instead is dumped, either on the ground or into a conventional toilet.
  • You are required to lay a natural, absorbent material, such wood shavings, coconut fibers, or peat moss, to name a few. This material removes moisture from the poop to help control odors.
  • Many composting toilets include a fan to suck odors out of the toilet and into a hose that vents outside.
  • You can either dump the contents into a larger composting bin to finalize the composting process, or dump it into a vault toilet found in most campgrounds, or dump into a trash dumpster.

Can You Stand While Peeing into a Composting Toilet?

Yes, but it can be messy with most composting toilets. Most composting toilets don’t have a seat that lifts up for peeing, though the Kildwick Composting Toilet (pictured above) does. Moreover, the bowl itself is divided into two halves… the back half for poop, and front half for pee.

Most composting toilet manufacturers recommend that guys sit down to pee.

Can You Barf and Diarrhea Into a Composting Toilet?

Yes, you can still barf into a composting toilet and diarrhea is totally fine too. Both should go into the poop bin. You may want to add more absorbent material afterwards to make sure the compost stays relatively dry.

Will a Composting Toilet Attract Bugs?

Yes, they will, but no more than a conventional RV toilet. Composting toilets will require you to keep the lid closed when not in use, and the lids are designed to prevent odors from escaping and bugs from getting in.

How Difficult is it To Install a Composting Toilet?

The steps to installing a composting toilet is not really that difficult. Anyone can do it, it just requires a fair amount of time, and finding a 12 volt circuit you can tap into…

  • The hardest part is removing the conventional toilet from your RV, if you already have one. You’ll have to turn off the water pump, remove the water line connection, and then unbolt the toilet from the floor.
  • Most people mount the composting toilet right where the old toilet was. You won’t need the old water line connection.
  • If your toilet comes with a built-in fan, you will need to locate a 12 volt wire inside the wall somewhere (perhaps by the light switch, or the ceiling fan) and run it to the toilet. Note that some manufacturers offer an adapter that plugs into a wall socket instead.
  • The Kildwick Composting Toilet (pictured above) is unique because it’s designed to be portable. You can move it around the RV, or move it outside.
composting toilets

How to Use a Composting Toilet

Here are the steps to using a composting toilet:

  • Before using the toilet for the first time, spread enough absorbent material (wood shavings, coconut fiber, et al) into the poop bin to cover the bottom completely.
  • Sit and do your thing. Each brand and model of composting toilet has its own way of dividing poop and urine, but all are designed to be done in the same sitting (or standing).
  • Toilet paper can be tossed into the poop bin. Make sure to use rapid dissolving toilet paper (RV toilet paper).
  • Throw some more absorbent material on top of the poop (if you’ve had a wet one).
  • When the poop bin has filled up, dispose the waste (see below). Some brands of composting toilets use a plastic bag liner to make removal easy.
  • Clean your composting toilet regularly to control odors and stains.

Do Composting Toilets Smell Bad?

Smells wafting from a composting toilet can vary from none to a lot, depending on three things…

  • If you use plenty of absorbent material, and
  • How hot and humid the weather is, and
  • If your composting toilet has a built-in fan.

Otherwise, if you take the time to manage your composting toilet properly, you’ll find that they may actually produce less odor than a conventional RV toilet.

Probably the biggest reason why conventional RV toilets can smell is because the black tank has mixed both poop with water and urine. The moisture is what allows bacteria and gases to build. By contrast, a composting toilet is supposed separate poop from urine, and then use absorbent material to dry out the poop. As long as you are diligent about doing this, a composting toilet should (in theory) not produce any smell.

Where to Dispose of Composting Toilet Waste

The urine bin can be dumped on the ground. It’s actually biologically safe in that it contains no live bacteria or virus.

As for the poop bin, it is illegal to dump solid waste from a composting toilet directly on the ground or in a body of water. This is because solid waste needs at least 120 days to fully compost and become safe for fertilizer use. Here are options on where you can legally dump…

  • Vault toilet or pit toilet at a park or campground. Assuming you can dump the contents of your poop bin without spilling on the floor or all over the vault toilet itself. If your composting toilet uses a plastic bag liner, you cannot throw the plastic bag into the vault.
  • Trash bin. Dumping human excrement into a trash bin is actually legal in most cases, but only if it is contained inside a plastic bag and tied shut. Landfills are regulated at the County level, and thus, this is based on the laws of each county. But, many counties have made it legal to dump human waste in landfills.
  • In your own backyard composting bin. This is actually the intended use of a composting toilet. You’re supposed to mix the solid waste into a larger composting bin, along with leaves, grass clippings, weeds, and other organic materials. It generally takes about 120 days for human waste to break down into a biologically safe fertilizer.
  • Burn it. You could actually toss the contents into a campfire, but only if you make sure it has burnt completely down into ash. We only recommend this if you’ve already built a strong, and very hot fire first. You might want to get some distance from the fire, because the smoke can be nasty.

Is a Composting Toilet Any Better Than a Five-Gallon Bucket?

In theory, it’s not much different.

Technically speaking, a 5-gallon bucket is a kind of composting toilet. You can toss an absorbent material in the bottom, and use it only for pooping. You will have to pee somewhere else. Moreover, you will want to make sure you line the bucket with a plastic bag (in fact double bag it) for clean and easy removal.

Believe it or not, many van dwellers use the 5-gallon bucket.

However, a “proper” composting toilet can be used for both pooping and peeing. They do a better job of controlling odors, and they look nicer too. Moreover, most composting toilets have larger poop bins, ranging anywhere from 8 gallons to 10 gallons.

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