Indoor, "modern house" composting toilet?

I'm trying to convince my other half that we can turn the downstairs bathroom into a composting toilet, and it wouldn't smell awful or be tonnes of work.

He's not a stranger to composting toilets (having used them in Bolivia- a non-separating toilet, and Ecuador- a separating toilet), but the ones we used in rainforest aren't things i'd want in my house, and i'm trying to work out if one could be suitable for indoors?

Its a ground floor room, no digging allowed as its on a solid concrete floor. There is currently no toilet in there, but there is plumbing for one. Its a vaguely-modern rather air-tight house (ok its a really old 1905 house, but it was refurbished and made quite airtight only a few years ago). The room is right next to the external door. We only have a small garden, so I could have room for 2x 1m cubed compost bins, but probably not much more (I can easily fill that much compost bins in a year with just garden waste, i'll have to try chop and drop a bit more perhaps!).

I've read the humanure handbook but i just don't have the room to do as that suggested. I was hoping a urine separating arrangement would produce less bulk (a lot less cover material in use), I could drain the urine to a tank for garden/allotment use in spring/summer, and into the existing plumbing in winter when everything is frozen. I could put a fan in, to draw air out of the house through the toilet to ensure all smells go outside (theere's a big hole in the wall is an appropriate place- used to be a dryer vent but i don't have a dryer). Think this would be sufficient?

Yay or nay? Any experience? Case-studies? Online thingies i could show him? Better ideas? I didn't mind the ones in the rainforest, its just my house has a lot less airflow, and whilst the odours weren't horribly offensive, they're not really suitable for the whole house.

A friend of mine locally has one of these: https://www.sun-mar.com/prod_self.html

The toilet is in their guest house/office and is used by 4-5 people per day (husband owns an ornamental welding business, also on site - the toilet is used primarily by his workers). No smell at all. But pricey.

Edit: They actually have this model which is the non-electric version. https://www.sun-mar.com/prod_self_exce_ne.html

Don't know if you have sorted out your compost toilet for in the house yet but in case you haven't I would suggest checking out the Bio Lan toilet from Finland. We have had one in the house for a year now and I would recommend it. It is a bit expensive at 1300 euros but has really been good for us.
The air vent that you have already would be good for your air vent for the toilet. It has a rotating drum that keeps the waste in place until composted and then empties into a small bucket. You only have to empty the bucket about once a month and it doesn't smell. Well worth a look at. Good luck.

Hi,
We bough our land and it had a sun mar toilet already in the cabin and I tell everyone I know how much I hate it.
Couple of big problems:

-you MUST purchase their product to spray in to the toilet or VERY bad things can happen.

-if someone fails to read your sings telling people to not touch anything on the toilet, simply close the lid, it will mess up the composting process. Its amazing how many people ignored the sign and turned the handle on the side of the toilet. I could tell b/c when I would go to use it the barrel would be facing the wrong direction (ie not in the "open" position to receive the waste. Think sideways barrel with a "door" cut out of it) and often "waste" would be on the part of the barrel not designed to come in contact with poop.

-To much urine in the toilet all will put things off.


this lead me to the design flaw in this toilet, when it goes bad you are emptying your toilet (if it is the self contained one) from a flimsy plastic tray not designed for anything but perfect compost.

After we had 2 guests stay with us for 5 days (grand total of people 4) our toilet malfunctioned. It began oozing brown liquid out the bottom slowly flooding our bathroom.

We now had to bail out the toilet. Grossest thing I've ever done, and I've given birth.

There must be better companies, failing that the alternative models that are NOT self contained would eliminate most of the problems.

I have two different Sun Mars here, one in the cabin and one in the big house. The one piece unit is probably what you would need. Hook it up to a 4" vent through the ceiling/roof, get yourself a 12 volt power source to run the small muffin fan that sits at the bottom of the vent pipe, and a small hole through either the wall or floor to run the drain through should it ever be necessary.

I actually plug a 12 volt adapter into the wall outlet (110V) so I don't need a battery to run the fan. Clean and simple.

I've had the one in the cabin for 17 years and the one in the house for about 5 or 6 years now. I think I paid $950 (Canadian $) for the one piece unit in the big house. They are easy to use, easy to keep clean, and no smell. You can use peat moss (recommended) to add to the toilet. But I have been using planer shavings for many years without any issues. One garbage bag full of planer shavings seems to last at least a year.

We have an Envirolet compost toilet here - it runs on electricity (you can buy it with a small solarpanel) and uses a little water - 2 dl (they have a water free option too). The toilets themselves are porcelain and with a pedal like those one airplanes. I wouldn't say that our start up have been smoothe, but reading the manual before you start using it might have prevented 99% (or 100%?) of the problems we've had

Dawn, the unit I have in the cabin sounds something like what you have. There is a regular looking toilet upstairs with the drum receptacle immediately below in the utility room. It connects with the usual 4" plastic pipe. Way back when, I seem to recall having the occasional issue, and that revolved around the drum getting too much liquid accumulating in the bottom.

I never add water to my composting toilets any more - haven't done so for years. The drainage problem doesn't seem to exist any more. Once you get used to these composting toilets they are so convenient and trouble free that I don't know why everyone doesn't use them.

I empty the tray maybe every two or three months at the most. It really is so little work. I keep a 5 gallon bucket of shavings in a small cupboard in the bathroom and use a sugar scoop to add the shavings to the toilet.

keith s elliott wrote:Dawn, the unit I have in the cabin sounds something like what you have. There is a regular looking toilet upstairs with the drum receptacle immediately below in the utility room. It connects with the usual 4" plastic pipe. Way back when, I seem to recall having the occasional issue, and that revolved around the drum getting too much liquid accumulating in the bottom.

I never add water to my composting toilets any more - haven't done so for years. The drainage problem doesn't seem to exist any more. Once you get used to these composting toilets they are so convenient and trouble free that I don't know why everyone doesn't use them.

I empty the tray maybe every two or three months at the most. It really is so little work. I keep a 5 gallon bucket of shavings in a small cupboard in the bathroom and use a sugar scoop to add the shavings to the toilet.

Ours is standing outside and connected to two toilets (in the future we plan to host work-shops etc. in our house, so we have two toilets). We do need the water, I think - but the problem was that I accidentally shredded the paper at the bottom when I should have areated it... which made the whole thing fall into the tray, without having been composted first, which then clogged up the system .... bla bla bla. So we had to empty it and it was gross to say the least.

Now it drains, but it smells... which I suspect is because we 1) forget to add pea-moss 2) forget to areate it (we have had a lot on our plates lately - today we are taking the day off, for the first time in 6 months).

Originally I was also going to have two toilets and the one drum. But never hooked the second toilet up. Still sitting here in a box unopened!

At the end of every day I turn the handle 21 times. That is three full revolutions of the drum inside. Every time I empty the tray, about every 3 months or so, I immediately fill it up again from the drum and let it decompose until the next cycle. Honestly, there is hardly any smell of any sort from the tray. It smells more like fresh earth than anything.

In order to avoid using water with the separate toilet type, just hold the lever open while you're attending to business as it were. The less liquid, the better the system works. Do you have the little muffin fan in your vent stack?

keith s elliott wrote:Originally I was also going to have two toilets and the one drum. But never hooked the second toilet up. Still sitting here in a box unopened!

At the end of every day I turn the handle 21 times. That is three full revolutions of the drum inside. Every time I empty the tray, about every 3 months or so, I immediately fill it up again from the drum and let it decompose until the next cycle. Honestly, there is hardly any smell of any sort from the tray. It smells more like fresh earth than anything.

In order to avoid using water with the separate toilet type, just hold the lever open while you're attending to business as it were. The less liquid, the better the system works. Do you have the little muffin fan in your vent stack?

We have a fan - I don't know if it's a muffin fan.

The only problem is the smell right now - oh that and the drain filled up w. sand somehow... but it still drained, just out on our courtyard... But I do think that if we remember to areate it, and add peat moss the smell will go away

Yes, it's probably a little muffin fan that is inside the bottom of the vent pipe. At least it is on the SunMar.

I don't understand why you are having your drain overflow all the time. You must be putting too much liquid in there. Yes, peat moss is a big help...the coarse kind is recommended. You can add stale slices of bread, planer shavings, small amounts of sawdust etc. It all helps.

Is the toilet and receptacle sitting dead level?

Once you get the liquid under control, I'm pretty certain the odour will vanish.

keith s elliott wrote:Yes, it's probably a little muffin fan that is inside the bottom of the vent pipe. At least it is on the SunMar.

I don't understand why you are having your drain overflow all the time. You must be putting too much liquid in there. Yes, peat moss is a big help...the coarse kind is recommended. You can add stale slices of bread, planer shavings, small amounts of sawdust etc. It all helps.

Is the toilet and receptacle sitting dead level?

Once you get the liquid under control, I'm pretty certain the odour will vanish.

I don't think we have a liquid problem honestly... there is a drain, but it is very very little that flows out, and it is designed to do so.

OK, well maybe it's not so bad then. If there isn't much in the drum yet, that may be why it isn't working as well as it should. Once you get some volume in there, they seem to work better.

I hope so

I tuens out I wasn't completely right about the no water issue in the bottom of the compost toilet there is a tray, that you use to empty the toilet - this is designed so that it fills w. liquid and overflows and then runs to the filter (to ensure that no solids get to the filter). Well - the technician at Envirolet admitted that it is a design flaw and that we should put holes in it to drain it. We did, but they are clogged - ie. the tray is still full of liquid. Next time we empty the toilet we will make the holes bigger I think. All the liquid does evaporate before it exits the system though - our banana, papaya and papyrus have all died from lack of water

We installed a higher chimney - because it was sitting er under the out hang of the roof, and the small windmill ventilator on top could not fit there (so we had et installed it). This has reduced the smell significantly (now there is a slight smell on the opposite side of the house). I suspect the smell to disappear completely when the drainage works as intended.

Now - the peat moss that we use apparently has a lot of eggs in it - a swarm of flies come out when we open the toilet. Envirolet recommends adding diamocateus (?) dirt 3-4 days in a row - but adding peat moss again will just have the flies return. We have a ton of prunings from our olive trees - if we run those through a wood chipper, could we use it in the toilet or is olive wood too hard? Could we add black soldier-fly larva to the system (I have heard they kill other flies?)

Sorry to hear about the tray problem. I would think that since the company admits it is a design flaw that they would adjust the design and give their customers a new version of the tray at no cost. I must say that I have never heard of a tray which doesn't let the liquids pass through. The liquid will sit for a short while on the housing of the unit, from where the vent system evaporates the liquid slowly into the atmosphere.

The chimney is a very important part of the system. It should most definitely exit well above your roof. As far as I understand the same applies to the toilet vent as to a woodstove chimney. That means that your vent should be at least two feet above any point of your roof within 10 feet of the vent pipe. If you are still getting odour on the other side of the house, a higher exhaust vent may eliminate that. There is a sort of laminar flow of air over your house as the wind passes over and around the house. The boundary layer of air shapes itself to the house if you will. The higher you get the vent exhaust, the farther away from the boundary layer of air it will be, thus less odour.

I'm not familiar with black fly larvae, but it might not hurt to try. Probably easier to try and find an alternate source of peat moss. I use all sorts of different wood shavings here instead of peat moss, and I think most of it isn't really that good at decomposing, yet it seems to work OK. Olive is a hardwood, and if you can chip it small enough it just might work. It would be worth a try anyway. Perhaps if you chipped a whole lot of it and then heaped it in a pile and added water, the decomposition would start first. Then maybe add some partly decomposed mix to your toilet to see if that would help. Adding stale bread slices will sometimes help as well.

As you say, once the tray problem is addressed, the problem should be self eliminating.

This doesn't really address the rest of the thread, but did you see this thread Burra posted a few weeks back?

That looks great, thank you!