Saturday, December 2, 2023


What’s the deal with composting toilets?


Here’s a question from a reader of about boondocking. 

Hi Bob,
What are your thoughts about using a composting toilet and then combining both the gray and black tanks as a gray tank? I have read that you can dump gray tanks when boondocking onto the local vegetation. Is that true? So, with an ample solar power system, a composting toilet and a fresh water tank refill pump system, would boondocking durations then only be limited due to food and other expendable supplies? Thanks. —Ken W.

Hi Ken,
I have had no personal experience with composting toilets, though I think they are the wave of the future for waste elimination processes into two separate operations (peeing and pooing). The liquid flows through two small holes into its own separate portable container, while the solids drop into its portable container. But you still have to get rid of the contents of each container, either into a campground toilet or dump station. Both are ecologically viable as “organic fertilizer” that do not have to go into a sewer, but you may have a hard time convincing a ranger or campground owner if they see you dumping your containers on their plants or on the ground.

Composting toilets need no plumbing connection

But all that is not as gross as it may sound. Most people who convert to composting toilets adjust and do not intend to go back to the old ways. However, there is not enough space in this post to thoroughly deal with the composting toilet idea. Instead, I will refer you to two RVing couples, both of which have used and studied composting toilets and have websites that explain in more detail exactly how they work, including videos. They are both worth watching before you make your decision. And yes, you can eliminate your black water tank or combine it with your gray – or install another potable water tank in its place. That would certainly extend your boondocking time from days into months. 

Watch the video from The FitRV website titled “The Straight Poop on our Composting Toilet,” and this one from Gone with the Wynns. Good luck. 

Read more about boondocking at my BoondockBob’s Blog.
Check out my Kindle e-books about boondocking at Amazon.

Do you have a question for Bob? Email him at bob.rvtravel (at) .

##RVT814; ##RV123




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R M Roberts (@guest_14445)
6 years ago

I watched both videis and came to the conclusion that I’ll stick with my black tank. It seemed obvious that “gone with the wynns” were obviously “selling” something, and “Thefitrv” videos was an honest assessment. “Nuff said”…….

Mike & Louise Bacque (@guest_14098)
6 years ago

We had a composting toilet, in fact the model shown in the photo of this article. We can also attest to the fact that solid materials aren’t composted to any significant degree and that crystals in human urine get caked inside the urine container. This requires frequent high pressure water spraying to clean out the container. The solid waste needs to be kept in a moist state in order to avoid odours. We found that the small computer type fan which is designed to whisk odours away contributed to the top layer of the compost medium drying out and resulted in odours. We also used the black tank as a grey tank however, we couldn’t count on simply adding both tank capacities to determine a new grey water capacity as we found that water equalization levels depend on configuration of the tanks and plumbing so that in effect two 40 gallon tanks may only fill to a combined 70 gallons instead of 80 gallons. We sold the unit and decided against a composting toilet for our next unit as we tired of handling our poop. We find that black tank waste is easier to deal with in the conventional method of sewer hose to sewer inlet.

Greg Illes (@guest_14012)
6 years ago

Composting does take a little more time and attention, but being free of dump stations is worth it. Not to mention the increased endurance by not using water to flush. Probably not a great choice for the “Ewww, poo!” types — but it’s not smelly at all really. It’s a heck of a lot better than the brown sewage flowing out of a typical black tank.

Rich (@guest_13886)
6 years ago

The one thing that has discouraged me from converting to a composting toilet – despite all the apparent benefits – and which I have not seen any RV user address – is that the compost is not quite ready for prime time by the time you need to offload it. It’s just not broken down sufficiently. Stationary users have no problems – they can hold onto the waste at their location indefinitely, so it does eventually become “just compost” but RVers don’t have the luxury. Has anyone else looked into this? If there were compost stations where you could offload your “unripened” goods, I think it would present the best solution – but until there are, it’s still a no-go for me.

Lisa Cantrell (@guest_13918)
6 years ago
Reply to  Rich

No the compost is still a long way from prime time so while on the road we bag it and throw it in a trash bin. I have had no problem doing this and do not find anything socially awkward about it. You see used disposable diapers in these bins all the time.
When however we have been parked at a friend’s or family member’s and they have an area where it is appropriate (woody, not near water, or not “cultivated”) I toss it there. Having done this in south Florida, upstate NY and several locations in the west I have been careful to watch for critters who might be attracted and there have not been any. Our dog, who finds cat and goose poop to be delicacies doesn’t even give it a sniff. So, in these areas I don’t give it a second thought anymore. It should not be used on food crops but even horse manure that we used on our organic vegetable gardens we did not use until it was a year or more older if applying to food crops.

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