Composting Toilet Saga Part V

Macy M25 comments14539 views

Literally two weeks after writing my How My Composting Toilet ACTUALLY Works post how there were basically no issues I noticed flies… in the house, not particularly concentrated in the bathroom but it’s a small house and they did find the toilet… there is no telling where they originated but I am fairly certain it was not in the toilet.  The same week I noticed them I had planted my kitchen window herb garden and bought a bunch for fruit (they looked like little fruit flies…), switched out my bulking material from the standard sun-mar brand to the mix of sawdust/peat moss AND bought a new house plant, could have been any of those…  I decided to treat the toilet first though so the problem didn’t get worse.  These are a few things I have done and some of the things I am considering doing that I’m looking for feedback on.

First I got some diatomaceous earth which supposedly works great as a natural pest controller in sort of a morbid way.  It is the microscopic crushed remains of fossils and shells and basically makes hundreds of slivers in bug exoskeletons, killing them.  It is too fine to be of any harm to pets, kids or myself so it was a good solution I thought to start at.  As a side note, I read it works really well as a flea and tick protectant on pets, Denver may be getting a DE dusting soon…

I poured about a cup of it into the toilet bin and went on as normal.  I did notice a decrease in the flies in the actual toilet but not in the house.  Again, because I know people will think this is gross, I am fairly sure that they originated from either my herbs, a bad banana or the houseplant I bought, I have had the same flies infest my big house about this time of year and there was no composting toilet…  but because there IS a composting toilet, a hands off one at that it becomes a bit of a bigger problem to get handled ASAP before they can take up ownership of the toilet… Long story short using a little diatomaceous earth in your composter seems to have an effect on any bugs that may or may not be in there, I am finding it to be a helpful additive to my bulking mix…

OK, now onto another Sun-Mar rant of sorts… One of the other things I mentioned that changed is that I have switched my bulking material (the sawdust stuff) from the sun-mar brand that came with the toilet, which has been nice, to just the standard construction waste sawdust mixed with peat-moss (could ALSO be a factor in the little bugs…).  I don’t like it as well just because it is a process to mix together and it seems a lot more dense (not ‘fluffy’), not as effective at absorbing the liquids so they can be evaporated… I went to order some more from Sun-Mar along with some more microbes just for good measure.  The total was about $43 which I was ok with and then I went to check out and they want $38 to ship that!  I checked on some other products, I was considering buying 5 bags of the bulking material (an additional $70) just to justify the enormous shipping rate but doing that brought the shipping up to $101!  Basically they charge you double if you want the product shipped…  not cool Sun-Mar, not cool.  Once again I am not impressed with their business model, I would think they would make things more accessible to individuals…

I have decided to go with their competitors microbe mix, Envirolet Compost Accelerator, they seem to be basically the same thing, same cost but much different on the shipping charges… As for the bulking material I may just get some hamster bedding or something a little fluffier, anyone have any suggestions for that?


Another totally separate thought that I would love some feedback on, might be a bit gross for some readers…  I did a little project with the City of Meridian on vermicomposting.  I have since given the worm bin back so some 1st graders can use it but I still have my worms which are troopers… I was wondering if there are any issues using red wigglers in a composting toilet?  I read a little article on it last night from and it seems like a valid option…  Does anyone have experience with this?  It seems that they may be better suited to a composting toilet than just kitchen scraps and sounds like things would go a lot faster.  To date I have followed Sun-Mars directions to the tee and after one year I emptied some waste into the drawer to ‘finish’

This is what that looks like
This is what that looks like

It all looks on point and about exactly what they said it would do, but I am wondering if I am using this composter to it’s full potential.  It seems like, since I am not at full capacity (2-4 people full time) I may be able to put vegetable scraps and the like down it as well.  Am I just asking for trouble by doing that though?  Unless I hear good reason not to I think I am going to stick my red wigglers in there (the website says to acclimate them to the different waste a little first or I could shock them and kill them) and use my toilet as a full-on composter.  I am not too worried about voiding a warranty with Sun-Mar, they have had absolutely atrocious customer service anyway and didn’t even warranty the product that arrived broken…  its doubtful they would warranty anything at this point anyway.

Pros would be faster composting, and a self sufficient system basically.  The cons would be that I don’t have easy access to the bin so the worms are pretty much there when they get there, I can’t maintain them…  It MAY mean I will have to get down there and maintain them manually at a point if it is a complete fail (gross). This is a project in learning though and it seems like that makes plenty of good sense.  The one thing they do say if you use worms in a composting toilet is to use plenty of bulking materials to absorb the ammonia and salts (pee) so that the worms don’t get killed by it… they suggested ripped up cardboard/newspapers…

So I guess I have a few questions:

  1. Do people have suggestions on a good/’fluffy’ bulking material for my toilet?
  2. Does anyone have experience combining vermicomposting with their composting toilet?
  3. Passively asked, has anyone had fly bug issues when it comes to their composting toilet and any ways to mitigate them?





  1. Those little “fruit flies” commonly appear with produce this time of year, in my experience. I keep a pre-compost bin in the kitchen, and I sometimes get a little cloud of them around it.

    To get rid of your current infestation, put all of your room-temp fruits into a bucket, wait a bit for the flies to settle inside, then put a lid on it. Take the whole thing outside and take the lid off. You’ll probably have to repeat that a couple of times and keep your produce and fruit in the fridge for a while to prevent another swarm.

    The are also attracted to kitchen scraps, so if you have a pre-compost bin, be sure to keep a tight seal on the lid or store them in the freezer, instead.

  2. No experience except to say that you want to be VERY careful (wear a mask) to not breathe in diatomaceous earth, as it will shred your lungs. I bought a big bag of it for dog flea patrol, but then read this & have been afraid to use it because my fluffy furry friend buries her now in her fur when biting bugs. So I’m saving it to spread along wall crevices if fleas ever get bad.

    Also, it might be a waste of $ to use in compost toilet, since it is useless as soon as it gets wet. I also wonder it it would kill the good bacteria that you are adding . . .

  3. Hi,
    I use a composting toilet ~ the humanure –basically a bucket and I only use peat moss. Seems to work great but then I am not composting, per se in my toilet, I have an out door compost pile that is segregated from water, food sources and works great with no bugs or smells in doors or out at the compost pile.
    Not sure about worms or the other questions you have. The humanure system works great but you do need access to a outdoor compost pile.
    I have used this for three years.
    I have heard from other folks using composting systems that they no longer use sawdust due to molding problems (holding moisture longer).
    I dont have any experience with this though.
    Good luck

  4. We are thinking we will get EcoJohns basic waterless composting toilet. I hope you get some responses about the bugs because I am curious now…
    Seems like it may be the same problem anyone has in a regular home with a regular toilet this time of year.
    We stayed at a place called East Jesus, and they had the simple bucket composting toilets and this was in the California where it was very hot and they had no bug problems…

  5. Hi Mini!!
    I have been using an envirolet for about 5 years! I am the only person living here. A few occasional guests. Yes flies are an issue. Diatomaceous earth helps a bit but not totally. It only works when dry. The fly larva seem to hank out in the lower chamber where the powder can not reach! I did try composting worms but they didn’t survive. You would need to be careful that there was no diatonaceous earth present at the time u introduced your worms. I am going to give the worms another try soon, they should improve the speed of composting. My model toilet is supposed to serve 4 to 6 people, I think this is impossible!! The composting chamber is far to small to hold and compost that amount. I love the concept of composting but the commercial designs are flawed.
    Please don’t add fruit or veggies, the skins already have fruit fly eggs and u will create a bigger problem. Actually fly eggs pass through the human body to the toilet and some hatch and multiply!!
    I had a good winter with no flies but as of last week i have a moderate flush, have to vaccume flies every day!!
    im Brown

  6. Guessing here…

    I would say it’s a crapshoot (see how I did that?!) as to whether or not the worms will work. They do not live in manure piles at barns (which is basically what a composting toilet is, only with people poo) but will gather in droves on the outskirts. The straight poo (even with bulking material) may be too much for them. If you remove it and start a bin, they will absolutely get at it once you add more bulking material (leaves, food scraps) in addition to the poo (like a regular compost pile).

    I think too much poo, especially of the human variety, which is particularly toxic, may tax their little wormy systems. This is all unsubstantiated guessing, though, just based on shoveling hundreds of horse stalls.

    1. You do not use earthworms in compost. The worms you use are redworms, aka, manure worms. I’ve been experimenting with using them to compost my own waste at home and have come to think of it as processing food for the worms. I do not include urine. For urine, I have a galvanized watering can that has a wide opening on top. This gets mixed with water for plants and it is one of the best possible fertilizers for plants. I have a separate worm bin for veggie scraps. I have discovered that the worms prefer the predigested food (aka, poop) and the worms in the bathroom bin are fatter and healthier than the ones in the scrap bin. I do sometimes add coffee grounds. For cover, I’m using shredded newspaper. There is zero odor.

  7. I’ve never had a composting toilet, but since you mentioned that you wanted a bulking material that is “fluffy” you may want to try and purchase a bag of aspen shavings from a pet store. Of the different wood shavings available for pets, these are by far the fluffiest!

    There is a good chance that the bugs are coming from the plants/soil, so you may want to put a light dusting of the diatemaceous earth on the surface of the soil where they’re growing. I had this same problem a few months ago when I replanted some houseplants with new soil. It was fine for a week, and then BAM, tiny little flies everywhere. It took me nearly 2 months to fully get rid of them, and I wish I’d tried the diatemaceous earth then.

    I don’t know what the requirements are for bulking material, but a FREE idea that came to me is to contact someone in the area who has house rabbits (NOT a breeder). Anyone who cares for rabbits properly in their home will have an endless supply (unless they compost it themselves) of “used” hay and bunny poop, sometimes with some recycled newspaper litter mixed in. I’m very active with the House Rabbit Society and could help find someone in your area if you’d like to try it out. Again, not sure if that would satisfy the requirements but it popped into my head so I mentioned it!

    Good luck with it all!

  8. I’m of the humanure school of thought as well, bucket and sawdust, with a pile out back for composting. Perfect simplicity with no smell or flies. Mr Jenkins suggests that hardwood sawdust rots faster than softwood, but I have had no problems with the softwood sawdust we have used for the last three years, we just leave the pile for two years before use on the garden. No experience with your other questions I’m afraid.

  9. Macy, order your special SunMar bulking material through They will ship it for free. No joke. Sunmar and Sears have a special arrangement. About the flies, every single person that owns the Sunmar has them. It’s something specific to the SunMar system. Don’t understand why that is but this is a common point of frustration for everyone that owns one (from the multiple dozen reviews I read about the SunMar).

  10. The feed stores in my area sell bedding pellets, a big bag for $5, that break down when moisture is present. Basically mini pressed wood shavings. The bulking is enormous.Before using as cat litter I stir water in to start them fluffing up. Don’t know if this would work with composting toilets.

  11. Hi Macy, Pete and I used to have a worm compost bin in our apartment and had a massive fungus gnat outbreak. They showed up after adding un-composted horse manure to the worm bin. It was especially bad when the temperature in the apartment got really warm; the warm temp made them hatch. We put our worm bin outside and vacuumed up all the gnats. After a few days we were fungus gnat free.

  12. You might want to peek at the Humanure Handbook if you haven’t already. I don’t totally understand how the “bought” composting toilets work, but I know Joseph Jenkins (of the bucket system) says to not combine food scraps in the bucket/toilet because of fruit flies. I’d imagine the same applies for your fancy toilet.

    I know why you don’t have the bucket system (because of composting on someone else’s land) but you might want to take a look at this:

    I envision using the bucket system in-house then emptying/composting in a big trash bin like they’ve done here. It’s theoretically portable (heavy, but portable) and totally contained, not draining anywhere, lid on it, etc. Then you could compost your food in the big bin as well. Like a contained composting heap.

    I’ve found very little in the way of vermicomposting humanure directly in the toilet, but there is a bit of info out there. As mentioned above, you need adequate cover material because the urine will kill them.

    I say just throw part of your worm stock wherever you want to try it, and give it a go. That way you don’t lose ALL of your worms and if it works, you can let other people know!

  13. Just in case you haven’t thought of this already, DE is unbiased in its slicing and dicing so it doesn’t mix well with little wormies.

    Also, someone mentioned a concern about inhaling diatomaceous earth. There is a BIG difference in food-grade and pool filter-grade DE, which has had chemicals added to it. I’ve known people who have been eating food-grade DE for years to help with all kinds of issues from killing internal parasites and detoxifying to relieving food allergies. Inhaling the natural stuff, even over prolonged periods, will cause less lung problems than talcum powder. There’s a bunch of good literature out there about it. Just make sure it’s the natural, food-grade stuff!

    1. Good to hear Holly, that is exactly what I have heard, it id definitely the food grade stuff. I didn’t think about it effecting the wormies though, good point!

  14. Hi Macy,

    I have lived with a couple of Sun Mars for the last decade. I thoroughly agree with you about their atrocious customer service; I could go on for hours with some real horror stories like the two months that we had to use the local grocery store every time we had to poop because it took them that long to send us a pin needed to fix the crank shaft (turns out we could have gotten the pin at any hardware store in 5 minutes).

    I have also had the dreaded flies. According to sunmar, it means the compost is too dry, but the idea of somehow running this perfect mix is ridiculous. I ended up ditching the compact I had in a rental cottage for a low flush toilet. The flies, overflows, smell etc just finally became too much.

    I still have the big unit in the basement of my house, flies and all. Am looking into alternatives, though I really want to compost the stuff, the unit is just crap (no pun intended!) and the design hasn’t changed since 1979. I’ve been curious about the worm thing too.

    I use big saw dust flakes mixed with peat moss. Couldn’t tell you if it works because I have flies and balls of compost, so something is not working, but I won’t pay the ridiculous price sunmar charges for a bag of sawdust.

    Good luck with everything; would love to hear if worms work!!

    1. Good, well bad, to hear I’m not the only one with a beef about the service, at a point I feel bad saying awful things about a business. This was so bad I don’t really feel bad about it though, I feel the need to warn others.

  15. The fungus gnats definitely do originate in the toilet. Diatomaceous earth helps, as does adding about 2 cups of water to the compost now and then. Seems strange but it works.
    My favorite bulking material is Dry Den compressed pine pellets from the local farm store. It’s $4 for 30 lbs. The pellets disintegrate into sawdust when wet. And it absorbs odor. (I also use it as kitty litter. In fact I just scoop the litterbix into the composting toilet.)

  16. I’m new to the tiny house world as I finished enough to endure a cold Minnesota winter. We have decided we want another option other than the outhouse. So the composting toilet seems like an affordable option.
    Unless you know different, I was thinking of using sawdust from a nearby sawmill, it’s free. My plan is to use a bucket and when it gets full enough, I will throw it in a plastic 55 gallon drum to complete the composting process. The drum will have holes drilled into it for aeration and rotated on a regular basis. The bucket will be placed in an enclosure with a toilet seat that will be vented to the outside.
    Are there obvious flaws in my ideas that you can see?

    1. That is pretty much exactly how my toilet works, only issues I can see is the cold, compost needs to be 54+ degrees in order to compost. It can sit out below that and be fine, just a holding tank basically but to actually do the work of composting it needs to be warmish. You Might paint the drum dark to help that out in the short-ish summers.

  17. I’m a little (lotta) late seeing your post on the composting toilet/gnat issue but wanted to chime in all the same. We too are having a slight issue with gnats. I’ve read they are fungus gnats and attracted to slightly too dry (but still damp) conditions…and LOVE the peat moss. The article goes on to say moisture level needs to be 40-60% (4-6 on a meter w/ 10-scale).

    As to the medium for covering, we currently use pine shavings but want to move to sawdust. The shaving are super high in carbon (a good thing) but slow to break down (not so good thing).

    We use a 55 gal drum which the hubby designed/modified btw. Good luck.

  18. I had a sunmar in my RV, it was horrible 1 out of 10…, so I bought an air head 9 out of 10 I love it!!! I use coconut coir, look for it at a garden store, one package lasts me 2 years, and it doesn’t take much room. I have been using it for 5 years, no issues with flies… and no smell.

  19. We have a floating Tiny House … a 28-foot cruising sailboat. Many of the composting issues are the same as with a land-based house, except that we don’t have the option of moving the compost to an outside location to finish.
    In our last 2 sailboats, we’ve had the AirHead. Never any problems or odor in many years of use. It’s wonderful!
    ….. BUT this summer, we’ve had the gnats. They’re there all the time, and quite a nuisance.
    Generally, the AirHead has liked drier coir/peatmoss, but I see that Dawn has commented that the gnats like the dry material. I think I’ll be adding a little more moisture. I am also planning to mix in some (food-grade) diatomaceous earth and see whether that works.

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