How My Composting Toilet ACTUALLY Works – A Review

I promised I would do a review on the composting toilet after it had been in use for a while, well after 6 months I thought it was time for my first in depth review, besides, I have had A LOT of questions recently on it :).  Waarning, there are pictures into my potty at the bottom (when I was shopping for one I wanted to see what they looked like in the bowl and it was SO hard to find a picture, I never did, so there is a picture of what a composting toilet looks like down in the bowl… if you skip the images you’re not going to miss much, just Denny drinking from the sink ;-))  You can read more about the toilet picking out and purchasing experience HERE, HERE and HERE, suffice to say, I was not happy with the level of customer service from the get go.   I am very happy to say though that the technology (or lack there of) of the composting toilet is great, I love my potty!  (living in a house for a while without a potty and you really learn to appreciate the potty!)

I went into this project very leery of a composting toilet, with the same thoughts as many people have, that it’s gross, that it will smell horrid, that it will be disgusting, that it will be a maintenance nightmare etc.  This entire project has been fundamentally about learning.  Even though the toilet was approximately 20% of my entire budget, and even though I had all of these concerns about the functionality, I took the risk to find out about this option first hand.  This is my experience:

The pros:  I like it way better than a flush toilet, honestly.  There are NO smells at all (there is a fan that creates a constant vacuum of air going to the outside).  It is warm when you use it (the unit I have has a small heater), no back splashing and no one can hear you peeing! All pros.  I have the added benefit of knowing that I am not contributing to a waste system where drinkable water is treated, used to flush a toilet and then has to be treated again, there is quite the process to that and a lot of energy/chemicals which I get to bypass, naturally and safely.  Like I said, I was very leery initially for the same reasons as many others but after six months I have had two issues and zero REAL issues, I will get to those in a moment.  All of that being said, I have not yet had to empty the drawer (based on full time occupancy – 3-4 persons – that would happen after about one year, and about 4 times a year).  Currently I am not even a quarter of the way to full but in spring I will do that drawer emptying deed, simply because it’s been enough time. I expect that it will be as painless as they say (pretty hands off and non-gross).  Other than that, even as expensive as it is it is cheaper than installing a septic system and it is not as limiting to finding a location as having to hook up to sewer, it gives me more flexibility.  So, those are my pros so far, now the cons…

The cons… 100% of people (I rounded up, there are those .001% that think differently) do assume it’s gross and disgusting and that I am a weirdo for choosing that option, that is the one drawback.  I do have a brother who refuses to use it, my partner did too, for a little while, but he’s fine with it now.  I wanted to have the most normal looking composting toilet so that it didn’t weird people out to use it, I think it does anyway though, which I understand, it really is ok though!
I mentioned above that I have had two issues, they are these:  First, the neighbor came over and one day when I was outside working and asked me when the toilet unit ‘cycled’ and if I could reset it for a different time because he and his wife like to hang out in their backyard in the hot tub late at night and it seemed to come on when they were out there and ‘really stinks’.  This was an odd question to me because there is no ‘cycling’ with this unit.  There is a fan that runs constantly, and vents out really high so that it is not noticed (and it does a really good job of being not noticed).  There is also a small heater in the unit that constantly runs, that is all, completely passive outside of those two components.  It made no sense at all that it was perfectly fine all the time except at this one time every night…  I racked my brain on it for a little while and then I noticed that that time of night was pretty close to the same time of night that I let Denny out to potty before bed.  Turns out he had taken up the habit of pooping in the alley, pretty close to where their hot tub is, and they are right, he STINKS!  It is slightly embarrassing that they think I could possibly smell like that, I don’t want to pretend that my poo doesn’t stink but seriously, it’s not nearly as bad as Denver’s poos… Once I figured out the issue I fixed it, he poops in the yard like a normal dog now and everything is fixed.  The neighbors still think I poo nuclear poos probably though… so I have that to think about every time I say hi to them!  So, issue one is a non issue…
Issue two, just the other night, maybe a week ago it seemed like the vent stopped working.  I have had the power go out before or have to be unplugged for a bit causing the fan to stop and it does start to smell in the house after a bit if I don’t seal off the toilet first.  I could still hear the fan running though, I completely couldn’t figure out what was going on.  Of course it happened late on a Sunday night, after it was dark and when I couldn’t see to fix it.  It couldn’t have happened when there was light, and on the weekend when I could do something about it :).   Even still, it wasn’t horrible and I pretty much convinced myself it was in my head and just my pregnant nose smelling weird things (I did cook asparagus earlier…)  So I went to bed, in the morning I could still smell it.  I asked James if he could too, he did, but it wasn’t like when the fan goes all out, that is very noticeable, this was hard to tell… I went back around by the vent and I could hear water dripping in it, there was no reason that should have been happening… by noon on Monday it was just fine, nothing at all wrong.  I am not positive what happened but I THINK that some snow may have fallen into the vent and partially blocked it, then as the day warmed up it melted away and everything was fine.  I did decide I need to get up there and put a screen over the vent opening though, I can see a bird or something making it’s way in the 2″ opening and nesting or something… So even issue two is a non issue, I’m fairly positive it was a weather issue, especially since it fixed itself with the warmer temps…
As you can read in the previous posts linked above, I chose to get a ‘fancy’ composting toilet (and paid the premium for it) so that I could have it in an urban area, it has to pass special inspections to be ‘safe’ as far as health services are concerned.  While this unit is not accepted everywhere it is much more so than say the standard humanuer version.  In most cases where it is not readily accepted it is most likely because the question has never been raised to inspectors.  Obviously a composting toilet is different than the standard flush unit in a few ways.  So, the ‘special’ things you have to do with my particular composting toilet (I am not speaking for the humanuer versions, I don’t know much about them):
  • When you first set up the toilet, after a week or so of use there is a little packet of bacteria that the manufacturer sends with the unit, you put that packet in the tank, it’s as easy as opening a package of ramen and dumping it out, that’s it!
  • At full time use, about twice a week there is a handle on the unit that needs to be cranked a full turn (I actually have grown to love this little activity, it feels like I am accomplishing an important bit of maintenance (and I am) but it also helps me mark the week, I crank it on Wednesdays and Sundays,  it’s really no big deal.
  • There is no special toilet paper you have to use, it all breaks down.
  • About 2-3 times a week you have to throw in about a cup of compost mixture (of a mixture of peat moss (40%) and Sawdust (60%), I have a ton of sawdust I saved from my build, I will be set for years on this!).
  • If the unit is below 55 degrees the bin acts as a holding tank only, composting slows/stops.  The weather does not hurt any of the components, it simply sits dormant until it warms up again.  (this is the reason I am waiting for spring to empty the drawer, I want to make sure it is in composting mode rather than just holding tank mode)
  • To empty the drawer you first fill it (cranking the handle in reverse) and then let it sit and ‘finish’ in the drawer for 6-8 weeks, at that point I hear it is just like potting soil and I will not be grossed out to empty it into my compost bin OR directly onto my plants (I still don’t think I can use the compost on my veggies, I may have to stick to the flower bed… )  This happens a max of 4 times a year (I expect I will be doing it once a year).

That’s it, it’s just different than a flush toilet, it hasn’t been gross in any ways [to me].  There are actually a lot more pros than there are cons [to me].  I would definitely suggest the unit to anyone else.  It’s weird to talk about potties but I am totally fine with it if there are any questions that are left that I haven’t answered, please, write them in a comment, I’m sure you aren’t the only one wondering.  I’ll do my best to answer them as much as I possibly can!

To leave off, one important thing I haven’t really mentioned, because my unit does it automatically, a good composting toilet will have a urine separater which does exactly that, separates the urine.  THAT is actually the stinkie part of a toilet… if you can keep the solid and liquids separate the smells go WAY down though urine will smell much faster and much stronger than poo.

The must haves of a hands-off composting toilet to me include a urine separator of some sort, a vent (preferably with a fan to make SURE the air-flow is going the right way – OUT), and depending on your climate a little heater to keep things above freezing and help evaporate off the liquids.  There are plenty of people though that are good with the humanuer version (5 gallon bucket with sawdust, they sell urine separators for those too…) I just didn’t like the maintenance of those and the fact they would definitely not be allowed in a city center because of health and safety regulations, for some they are a great and inexpensive option though.  Now for the pictures inside the toilet… turn away if you must (it’s really not that bad…)!

Because I can’t just leave it there I have included a video of Denny playing fetch in the tiny house… you can get a glimpse of my belly which is now HUGE! ;-)


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69 thoughts on “How My Composting Toilet ACTUALLY Works – A Review

  1. Thanks for sharing. I enjoyed it all….down to the video!! Question, did I miss what you do with the urine after separating?


    1. Sorry, I glazed over that, the unit itself separates everything down in the bin, the heater and fan are in part to evaporate off the liquids. I don’t do anything with any parts, it’s all self managing until its time to dump out the drawer.

  2. Ok ok. You convinced me! I always swore id use a regular, low flow toilet when i build mine. You have convinced me to to at least consider composing. You are right, doesn’t sound as bad as i thought it would be.

  3. Very well written!

    So you know on a regular toilet you clean down in the bowl and the interior sides of the bowl. Is that a possibility for this one? At least on the interior sides where the waste doesn’t sit but it definitely get dirty.

    1. Very good question, yes! You can! You can use warm water and a natural soap (NOT an antibacterial soap, you’ll kill all the good guys from the packet!). You definitely can though.

      1. What are the inside walls of the toilet made of? Porcelain? Plastic? It looks black in the pictures. Doesn’t that make it difficult to find and clean anything that has splattered on the walls?

        1. It is a black plastic, it is black exactly for the reason of hiding anything that has splattered on the walls. It is important not to use any cleaning chemicals in composting toilets, you can use some natural cleaners or just soap and ‘natural’ soaps (no antibacterial soaps or you will kill all the good guys down there doing the composting work).

  4. Urban composting toilet at it’s best, glad there is a solution for you city lovers :) Mind you I still prefer my bucket and sawdust toilet; no smell, no hassle and only about 5 minutes a week of maintenance.
    Most importantly neither of us is using that most valuable resource of water or poisoning it with a host of chemicals.

  5. Wow! Macy.. this is the smallest composting toilet I’ve ever seen! I’ve been struggling with what to use for our tiny house. We are tight on space and the ones I’ve seen you have to step up to sit down. They’re tall and wide and would never fit. Is the tank below? Would you please give me the name of the manufacturer? I’d love to look it up.

      1. The inside unit definitely is, that’s why I liked it, its the tank outside that is bigger! It’s slightly bigger than a 55 gallon drum.

  6. Thanks for giving the follow up! So many of the people who write about alternative toilets just describe installation and then don’t get around to following up. Will you please post again after you do an emptying of the compost? As they say, the proof is in the pudding…

  7. So, this is a dumb question, but when you empty the contents, where do you put it? I’m guessing it’s not already broken down into composted soil that fast, right? Does it smell awful?

    1. Not a dumb question at all! So when emptying the contents you can put the final compost in your garden plants, I have decided I will only put it on non-edible plants even though they say it’s fine to put them on any :). I have not had to empty it yet but I will in June whether it needs emptied or not and I will make sure to talk about it. The waste stays in the bin a year or so so it is fairly broken down but there is a drawer that you empty SOME of the contents into and let it ‘finish’ for two months before pulling it out and emptying it in a garden bed. I am told that at this point it looks just like potting soil with no smell or anything, I tend to believe them because everything to date has worked just as they stated on the website (Sun-Mar). So far there are zero smells, the fact that the solids and the liquids get separated limits the smell a great deal. I would say separating solids and liquids is the best thing you can do to limit smells, better than a fan even.

      1. Thanks, Macy! I would have thought that it would need a lot more time before it became soil-like! So, there are two separate drawers, one for the earlier process and a second one for the finishing process?

        I also thought of another question. Since it has a separator that liquids go into, would it be possible to use a hook-on bidet with it? “Regular” composting toilets don’t accept liquids easily, so I’d written off the idea of a composting toilet until I read about yours. I’ve known people who have stayed in primitive places that use those, and you have to pee on a tree – which does not at all suit me :)

        A few months ago, after much research and reading, I added an attachable bidet to my regular toilet and stopped using toilet paper altogether… it has been a wonderful shift! It uses very little water, no electricity, and leaves me feeling much more clean and fresh. I also love the idea of less waste plus saving $ on not having to buy tp. I keep a bit on hand for visiting friends and clients, but that will last quite a long while!

        When I eventually have an off-grid cabin built, I am definitely considering using one of these but would want to use my bidet along with it. Do you think the added water would be a problem?


        1. Two separate steps, yes, one larger composting bin and then the drawer where things finish and get emptied, the drawer is much smaller than the bin since waste composts down to about 1/10th the volume. There are several designs that sound like they will work with the bidet you describe. You may not be able to make it work in a city center since you will probably need to have the fluids empty into some sort of seepage bed. In my unit the fluids drain through the main bin to the bottom of the unit where there is a heater and a small fan that evaporate them off. If there were more fluids there is a drain that they would come out of which is suggested to be tied to a seepage bed or a sewer line. The mechanics of various units vary but it sounds like it wouldn’t be an issue to achieve what it is you want to achieve at all! I strongly recommend composting toilets as a viable solution for what that is worth!

    1. It is in those links at the beginning along with some cautionary tales about their customer service or lack thereof, it is a Sun-Mar

  8. Hi Thanks for your great commentary Soooo… there are no odors detectable coming from the vent or holding tank, Right? Nothing that nosy neighbors could detect? Are these actually legal in suburban areas of California? Wonder where to find out and did you you need a permit for this ? Thanks again

    1. I have to say, Garlic Cat made me laugh out loud, really :). Yes, there are no detectable odors, the toilet vents 10-12 feet in the air and I haven’t noticed any. The neighbor complained one time because he knew I had a composting toilet and he asked me to have it ‘cycle’ at a different time so he didn’t have to smell it. I was of course mortified but also confused because there is no ‘cycling’… it just does its thing. Long story short, we found out it was that I was letting my dog out at a certain time and he liked to poop next to his fence… the guy could smell THAT and though it was me. I was still mortified but we got it cleared up and now he dog cycles at a different time :). If you were closer to 2 story houses you may want to vent up higher, should be at whatever level the roofs around you are and then there is no smells, they get carried away and dispersed even on less windy days… They are legal in many parts of the country, you would have to speak with your local plumbing code inspector to find out for sure. Hope that helps!

  9. Hi Macy I would like to have the model # and the manufacturer of your c. toilet .The above address only took me to your Tiny House site. Thanks

    1. You can find that in the three links listed in the first paragraph, I would just give it to you but there is important info in there about things to be aware of (I am not completely happy with the service)

  10. Thank you for such a great explanation. I have two questions… 1) can this type of toilet be used in the tropics? 2) do they have an equivalent technology to replace a bidet toilet?

      1. As long as the bolts that fasten the seat down are roughly equivalent to those on a regular toilet seat, and the toilet is capable of accommodating a little more liquid than it normally would, you should be able to attach a bidet adapter directly onto it. You’d have to have a water supply close by, though, to tap it into.

        1. The bolts are the same and the unit is a flush OR Dry unit so it sounds like a win. My particular set up is a dry set up so no water.

          1. Very cool that the bolts are the same! And the water doesn’t have to come from the toilet, the bidet has a water supply that just needs to be hooked up, a sink pipe close by will do just fine as long as there is running water of some sort available.

            My biggest concern for doing this was that the unit could accommodate the additional liquid in it.

            Also nice to know that this unit can be used for flush setup also!!

    1. There are three links in the first paragraph that take you to that info, I would just tell you but there are other important tidbit of info along with that info that I want to make seen too, I am not entirely happy with the company and how they approach (or rather don’t) customer service.

  11. This may be a random question, but on the model pictures from your link, it shows that the holding tank below is quite large, is there room for that under your trailer and still clearance from the ground if you were to ever move your home? It seems as though the below surface parts take up a lot of room…..

    1. My trailer is above wheel so there is more room than standard, I do dig down about 6 inches into the ground but I could also just put my trailer 6″ higher on it’s blocks. If I move I just slide it out and put it on the back patio. it is a large unit but I liked that because it makes it more hands off than others. i have to empty the drawer about once a year is all.

  12. Just back from the Mother Earth News Fair in Pa. and I looked (literally) into all the off grid toilet options there. I am also looking into one called the E-Loo out of a company in Texas. Really great to read your post, want all the info I can get before I make my decision. Thank you.

      1. Not sure yet, not building for another 3 years, site considerations will play a major part in my final decision. Will probably go with a self contained unit and the E-Loo would preclude that.

  13. Hi Macy. I find your posts so educational thank you. I have a question. We already live in a Tumbleweed Tiny Home and I want to convert to a composting toilet. Can you please tell me the brand you purchased and provide a link? I would like to get this exact toilet because I trust your research.
    Thank you

  14. Hi Macy, thanks so much for the great info! I am in the process of having my tiny house built (with a builder) and I wanted to use a remote composting toilet like yours but had a couple questions. First… will the part that goes outside be able to fit under a trailer? Or does that only work for houses with foundations? And something my builder brought up… if I have a rooftop deck on my house (above the loft which is above the bathroom), will the toilet need to vent right next to my deck? :-/


    1. each model is a bit different on dimensions, my trailer is not a drop axle so I have more room than most. Even still I did have to dig down about 6 inches to fit it. Mine is a trailer so it is certainly not just for foundations. The toilets vent at 12-14 feet, it doesnt matter where on your house it vents in proximity to your deck, a tiny house is not big enough to get away from it unless you vent it higher, which isn’t THAT feasible. I’m not sure how well it would work with a roof deck honestly. It is noticable on the roof… we found that out reroofing the shop next door to me. Hope that helps!

      1. Oh, okay. That’s what I was afraid of. :( I was really hoping to get one that composted outside of the house but I know I most likely won’t be able to dig down into the ground under my trailer (I’m going to be in a friend’s backyard). And yes that does help about the deck, I didn’t even think of that. So that venting be an issue with any composting toilet then, right? Even if it was a self-contained unit?

        1. I think the fan is the real difference, Composting toilets all work differntly, you can probably find a non vented self contained unit, it just gets more important how you use it. There is SO much difference in this area, A dry flush toilet may be a good option?

          1. It’s pretty confusing on my side too honestly! :) Did you ever think you’d call a toilet ‘pretty cool’? :D You’re doing great!

          2. Ha! No, I definitely did not! I was just talking to my friend last night and told her about this cruise I’ve been wanting to go on but had decided against it this year because I needed to use the $ for a decent toilet instead, lol. I heard myself and was like what?!? ;) Thank you, if you want to follow my saga as it unfolds too, my blog is Love yours! :)

          3. hahahaha! That’s awesome! I’ll be following along! Thanks for sharing the link! I love following along!

  15. I’m building with the help of my high school students. I ordered the
    and I can’t wait to use it. I liked it much more than the Sun-Mar only because I can empty the goods right out of the house and the urine diverter connects right into my greywater system. Next week our whole school PreK-gr12 is studying water and they are doing a whole unit on looking at toilets. I can’t wait for the students to learn about composting toilets. My facebook page is

    1. I partially wished I would have known of the Separett and/or the dry flush when I built! I’ll keep tabs to see how it goes, thanks for sharing!

  16. Macy, you mention the fan and the heater that are going all the time. How noisy are they? Would they be too noisy for having the unit in a bedroom? Also, what sort of electrical requirements do they have? Standard 120 volt? Thank you for sharing about this and inspiring others to consider this alternative!

    1. They are not noisy, I have to strain to hear the fan from in the bathroom, the heater is completely silent. it is a standard 120 v plug but could easily be hooked up to a small solar panel, very low draw. Hope that helps!

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