The Truth About Dry Toilets for RVs
When the subject of composting toilets comes up, most RVers reactions range from mild curiosity to shudder-inducing horror. The thought of treating human waste inside the RV scares many people. “Is it smelly?” and “Do I have to touch it?” are common questions. No one likes the thought of schlepping a container of urine through your living space. Or having to stir a tank of solid waste in a tiny RV bathroom.
But are these fears founded or are they RV horror stories of years past?
The truth is that composting toilets have been manufactured since the 1960s. Modern composting toilets are not terribly time-consuming. Dry toilets have less “ick” factor than a traditional black water tank dump station. Many who full-time or do a lot of boondocking are turning to composting toilets. Dry toilets are a way to save on water usage and to make fewer trips to the dump station.
How RV Composting Toilets Work
Composting toilets look like a normal RV toilet but use a non-flushing system. It is best to use toilet paper that breaks down quickly in the system. The toilets typically have a three-chamber system that divides solid waste and liquid waste into separate chambers.
Plant matter such as sawdust, peat moss, or coconut hull is used as a composting base for the solids. When solid waste is added to the chamber, a crank handle is used to churn the mixture. The natural microbes can start digesting the waste and breaking it down into beneficial compost. Later, it can be spread safely onto the soil over tree bases. Dumping the compost happens every 2-4 weeks with full-time use. At that time, you add new compost medium and are ready to go again.
Around 80-90% of the waste entering the toilet is liquid. The newer composting toilets use a fan and a vent system or a heating element that quickly evaporate the liquids so that you don’t have to dump them as frequently or at all (depending on the usage).
Most liquid tanks can hold a couple of gallons and are designed for easy removal and dumping if usage is greater than the evaporation rate. Because the liquids are separated from the solids, the chemical reaction from the ammonia and uric acid in the urine doesn’t have a chance to create the dreaded “port-a-potty stink.”
What About Dry Toilet Waste?
To correctly compost, a toilet must provide the proper environment with a balance between oxygen, moisture, heat, and plant material. This allows the bacteria and microbes to completely breakdown the waste into odor-free compost that doesn’t contain viruses and pathogens and is safe to handle. What is left is a nutrient-dense natural fertilizer.
The “dumping” of the resulting compost seems to be a sticking point for many people when considering composting toilets. For anyone who has done any gardening and used store-bought compost, you will not find a difference in what is produced with the toilet systems.
You should not see or smell any “original” contributions to the compost in its final state. In fact, many municipalities create compost from human waste as part of their wastewater treatment plans.
While the compost is safe to handle and use, it is not recommended to use the compost produced by the composting toilet directly on your vegetable garden as there is an internal heating requirement to ensure compost safety for produce that will be consumed. If you are squeamish, you can always wear gloves to provide further barrier between yourself and the compost.
Full-timers Drivin & Vibin reviewed some of the top Q&As on composting toilets in this video:
How to clean a composting toilet
Cleaning a composting toilet is easier than you might think. Check out this Do It Yourself RV article on 5 tips for a stress-free cleaning.
If composting toilets aren’t for you, you may also be interested in these Two Waterless RV Toilets For Easier Waste Management
We’ve been using a composting toilet for a year. We really like it for boondocking and there is no smell. You mentioned using toilet paper that breaks down…DON”T. TP goes in a separate can and gets discarded. It does not break down fast enough for the compost. You also mentioned there are three chambers, there are only two, one chamber for solid waste and one for urine.
It is a persistent myth that the solid waste compost is safe after such a short time. It should be disposed of in the trash, just like a baby diaper. We’ve encountered two west coast beachfront campgrounds that have banned vehicles with composting toilets because previous campers emptied their compost waste on the beach.
Composting toilets are the best for us usually empty the pee bottle every other day and the composting material usually lasts a month to six weeks. Full time RVrs for three years and 53,000 miles so far . One great tip is to add a half cup of sugar to the pee bottle this will eliminate any odor that can happen in warmer climates
Adding to my comment from last year, I should have been more clear that the solid waste should be dumped into a strong garbage bag before disposal, NOT just dumped loose into the trash — yuk! I use trash compactor bags.
I don’t get anywhere near a month out of it; with 2 users I empty the solids weekly, before there’s any smell. Trust me, you’ll know when it smells. I’ve never encountered signs at trash receptacles banning this trash. It’s unoffensive and contained.
The urine smells within a few days and mineral solids build up inside the container which are impossible to remove completely. Finally, after two years, I’ve found products for pet messes called “urine destroyer” or “digester or eliminator” are the only thing that works. I like the one by Resolve. Empty the urine container slowly into a toilet, rinse it and flush, then back in your RV, add a few ounces of urine destroyer and water. Fixes both problems of urine smell and buildup. Before that discovery I would have happily kicked the toilet to the curb for a better alternative. Now there’s virtually no smell or buildup from either the solids or liquids.
I’ve never tried sugar but I’ve tried vinegar which smelled awful and wasn’t completely effective. I also dilute some urine destroyer in a spray bottle and use it after each pee.
Heck. Nope. Been there done that. Disaster. Urine tank leaks. Mechanical problems. Nobody will service them. Nobody will take the compost. Not an RV dumpsite, and no campsite wants the compost. In many places it’s illegal to put it in garbage, down sewer or leave in “compost” pile. Plus a half filled compost toilet is heavy and since no one wants your composted crap, you get to tote it along home.
And DON’T put it in garbage. Not where I camp. It stinks. You will get kicked out. What to do with the unfinished “compost” is the real problem here, since the stuff you empty from acompost toilet is never fully composted. It should only be deposited into a raised compost bed so it can further decay into clean finished compost.
Lots of contradicting opinions and experiences….. let’s stick to the facts; 1) It IS legal to dispose of it in household garbage EVERYWHERE. It falls into the same category as disposable diapers because it is ‘non-flowable. 2) Some of it will not be composted or will not be desirable for compost if you put the paper in with it (yes, paper is compostable). Just double bag it becore you put it in the trash and you’ll be fine (legally and practically)….3) Forget all the ‘enviro-hype’ (IMHO, the biggest problem regarding composting toilets) that you are saving the environment and can dispose of it on the ground anywhere…YOU CAN’T. It is ‘waste’ until weeks of composting after the last deposit. It is not going to become a soil amendment for some time so it just needs to go into a landfill ALWAYS. 4) Don’t try to convince someone to take your ‘compost’ because it isn’t (completely). Just put it in an acceptable garbage container……..I like my composting toilet but am a realist about what it is and what it is not. If you want to use one (successfully) you need to be too.
While it may be legal some areas to put compost in the garbage, it’s NOT taken by some trash haulers and IS subject to local regulation. In New York, disposing toilet compost waste, like agricultural waste, is regulated and must follow 6 CRR-NY 361-2.3 d NY-CRR. I live in the Skaneateles Lake watershed for Syracuse, NY. Compost toilets were distributed to local residents who can’t have septic systems. Compost toilet waste is NOT allowed to be deposited on the ground in the watershed. Period. The city collects it from residents with such toilets. I owned and maintained 3 Sunmar Excel toilets toilets for 10 years, and became intimately familiar with all the positive and negatives of them. One of the negatives was the disposal of excessive urine. We were not allowed to use existing dry wells or gray water systems. So be aware that there ARE local regulations to follow and that disposing the waste is NOT legal in ALL areas.
Better yet, get a copy of:
The Humanure Handbook: A Guide to Composting Human Manure, the 4th edition is out now, and make your own.
I haven’t tried sugar but did use vinegar. I added about 1/4 c of white vinegar to the pee container after dumping it in the toilet at rest stops. The only issue is that it created salts (precipitate) at the bottom of the container but that dissolved back out with plain water and came perfectly clean. If you are using your rv for a few weeks or a month at a time, it is reasonable to return home and not dump the solids right away but let them continue to compost in the toilet (turn the crank every day or so to keep everything mixed) and in about a month it is really composted and can go in a flower garden (not for food consumption). If you are living in the rv full-time I guess you would need to dump in a trash bag. one problem I see is folks use strong cleaners in the solids bucket and those will interfere with the biotic action unless very carefully rinsed. The goal is to keep the bacteria happy and working.
Sugar vs vinegar? Are we talking about composting or catching flies?
I never hear any discussion of the waste that doesn’t go directly down into the composting container. From what I can see there is ample opportunity for solid waste to get stuck to the sides of the bowl. What happens to that waste? How do you clean that up?
Ed, yes, some solid waste may stick to the inside walls. Since you’re wearing disposable gloves, it can be wiped or scraped off. I invert the solids into a strong trash bag and then deal with any remnants, using either a few baby wipes or a disposable plastic spackle knife. This is the most gross part of the process. Nothing compares to a residential flush toilet.