Constructing a DIY Composting Toilet, by SF in Oregon

Here is my description of my do-it-yourself (DIY) toilet that works like a charm. This is how to deal with the “S” part of when the Schumer Hits The Fan (SHTF).

Of all the kludges I’ve built off-grid, I’m most proud of my toilet. As preppers, we tend to spend a lot of time on food (what goes in) but not so much on sanitation (what comes out).

If you are on-grid with a septic system, great. But as many folks in Texas recently discovered with their once in a generation below freezing storm and subsequent power outage, without water to flush, toilets don’t work.

Add to it that without power, they also have no ventilation, and without heat, just keeping the bathroom windows open is not an option.  It’s not just about bad smells, it’s then a health hazard.

Nine years ago I began building my off-grid retreat and one of the first questions was: “What about going to the bathroom?”  We have a big tick problem here (guineas to eat the ticks and dogs to chase away the rabbits and deer have helped), so I didn’t think that urinating around the house was a good idea. I have read that the smell of urine can attract the ticks.

Also, using the ‘bucket’ method (whether a 5 gallon bucket or the fancier versions) wasn’t working well.  While the urine and feces had a smell, add them together and it was much worse.  Wet feces goes through a different biological process than dry feces and the smell and end product is both more dangerous and offensive.

We think nothing of mixing solids and liquids since they get flushed down the toilet.  We never have to experience the end result of their mixing unless we live near a waste treatment plant.  Mixing the two and adding a flush of water makes sense in a modern world. Liquid slurries are easy to move from point A to B.  From your toilet, down pipes, into your septic.  Not so easy to move solids. So, what to do?  First, let’s separate the liquids from the solids. The idea is called a ‘urine separating toilet’.

First, I tried a urine separating toilet by Nature’s Head. It works for both men and women).  I had high hopes for this system, but found that it had multiple design flaws:

1- Urine going into a plastic container will eventually cause the container to accumulate a foul-smelling crud that is difficult to get out with the small opening in their jug, so you either deal with the inevitable smell or buy more of their custom urine jugs.

2- The urine container is small so it needs to be emptied frequently.

3- The feces goes in a different container that is ‘dried’  and the smell evacuated by a small fan.   This means that the system continuously generates foul-smelling air that has to go somewhere.  Even in good times, I didn’t appreciate the outside of my house having a place that smelled bad. In a time like what the Texas folk are dealing with, even if you run the small fan from a battery,  air going out requires air coming in and there goes your heat.

4-  The small computer fan they use is a place that the system can easily fail.  Without it, the unit doesn’t work as well.

5-  There is a bar that rotates in the feces container to mix it. The container is rectangular.  The geometry doesn’t work.  The mixing bar mixes a volume the shape of a cylinder due to the rotation.  The feces container is rectangular.  This means that you always have blind corners that don’t mix.

6- Once full, it is a disgusting mess to clean out the feces.  Put on elbow length gloves because you are going to be cleaning it out by hand each time, and you’ll never get it fully clean without a pressure wash.

7- The feces container is plastic, so the feces in it will cause it to take on a permanent smell.

Back when I got mine, a Nature’s Head cost $600. I’d be fine to pay the $1,000 they cost now, if they were a good solution, but they’re not.

Next, I tried the Laveo dry flush toilet at $684.  This isn’t a urine separating toilet.  Instead it uses custom bags and a vacuum to seal the urine and feces in a mylar tube.   You end up with ‘links of sausage’ mylar bags with the waste in the link, if you can imagine such a thing.


1- Because the wastes go into a bag, the unit does not take on a foul odor over time

2- Clean up is easy.


1- Power is required, but that’s not the main issue.  You can run it off a 12-volt battery for quite a while.

2- The cost is over a dollar a flush.  Before the world went mad, it was great for festivals, but this is way too pricey for home use.

If you have money to burn and only want to wait out a 1-week to 2-week power/water outage, then this is a fine solution. But if you want something more long-term and financially viable, no.

What about a composting toilet, you ask?

1- Very pricey.
2- Some require a lot of power.
3- I’ve heard a lot of stories about how they can fail.

Okay, lessons learned?

1- I want to separate urine from solids.
2- I want easy cleanup.
3- I want no power requirements.
4- I want no smell.
5- I want it to last about a week for 2 people

So, I looked around, but didn’t find anything that met my requirements.  Okay, time to start building (cue inspirational music)… “The greatest off-grid toilet ever”.

Building My Own

You will need the following:

1- Separett Rescue Camping 25 Portable Urine Separating Toilet. Available from Wal-Mart, Amazon, and other online vendors.

Use this to separate the urine and the feces.  You will only be using the seat, not the stand nor cover nor flimsy bags it comes with.  If you can afford the expense, then get the seat Cerakoated.  Remember: Anything plastic can and will take on the smell of what’s around it.

2- 5 gal Gray Steel Epoxy Lined UN Rated Bucket. $13 plus shipping. 5 gal Gray Epoxy Lined Steel Open Head Buckets (Lid Not Included) – 1272. Available from:

This is what is placed under the seat.  Yes, it must be epoxy lined.  Otherwise, the smell will pass into the metal.

3- Trash compactor bags.  I use Ultrasac – 771228 Trash Compactor Bags also available on Amazon. $15 for 40 bags.

Do not use lighter-weight bags.  Lightweight normal bags will pass the smell onto the bucket and are more likely to rip during transport.  Between the bags and the epoxy coating, the smell will not get into the bucket itself.  In fact, I now use these bags for household trash too.  The thicker material attracts fewer animals.

4-  A 2 1/2 gallon plastic jerrycan.  S 17470nat.  $10 each from
This is what you will use to capture the urine.  These have a 3/4” female thread on the cap.
FYI, you’ll need to drill a hole in the cap to let the urine pass into it.

5- Assorted plumbing parts.

A- A 3/4” NPT nipple.  This goes into the threads on the cap of the jerrycan.
B- A 3/4” NPT PVC valve.   This goes onto the nipple now sticking out of the cap on the jerrycan.
C- A 3/4” NPT barb.  This goes onto the other end of the valve.
D- 1 foot of black poly hose to go between the toilet seat and the barb.  If memory serves, the hose that comes with the toilet will not fit on the barb.

Now… make two of them.  Why two of the urine jug assemblies?  You will fill the urine jug before you fill the feces bag.  Plus, it’s just easier to be able to replace one jug with an empty one than find out in the middle of a storm that your jug is full and now you have to dump it to use it again.  This way you can wait until the snow/hail/rain stops to dump the jug.

Now, connect them as per the photo to the left.  The urine goes into the jerrycan, and when you transport it, you can close the valve without it spilling.  Just pull out the entire urine jug assembly from the seat and put in a new one.  You will want to replace the jerry cans every few months. This is because over time, they will smell, but if you are mindful to empty them regularly, you won’t notice much, even right at the toilet.   There’s probably a way to clean the jugs with RV enzymes or something. But I just get obtain new ones, as needed.


What to do with the urine?  If diluted 1:8 with water, you can use it as a direct fertilizer on your fruit and nut trees.

We’re almost done.

6- You’ll need a cover over the 5 gallon bucket when you aren’t using it, to contain the smell.  You can use silicone pot covers, but I had a powder-coated metal cover made for me.

7- A custom seat adaptation.  This is the only part you can’t buy off the shelf.  I had a metal shop make me a few of them.  Next ones I’ll have powder coated.  Didn’t get the height right the first time hence the bricks under the legs in the photo. The Separett brand toilet has 4 ‘slots’ that secure it to the seat, so this will take a little skill, but any forge/welding shop could do it easily. I was charged about $100 each for the ones that I had made.

8- Peat moss.  Just sprinkle some over the feces when you are done and that’s it.  A fine mist sprayer on top of the peat moss you put in makes it even more effective.    By the way, peat moss is very inexpensive, but you could just use dirt or wood ash or sawdust. Just saying, peat moss seems to work the best.

9- A portable bidet bottle (the white and purple bottle in the photo).  $10 on amazon.   Use this to ’flush’ any droplets of urine that don’t go down into the urine jug.

Once you’ve found a place to empty your urine jugs, just toss the feces bags into the garbage.  Yes, it is a gray area about putting human wastes into the landfill, yet diapers are allowed without any special medical waste treatment, so as far as I can tell, just don’t make a mess of things and you’re okay.  The bags I suggest are very very strong, so no fear of having them tear in transport.  Also, remember, since the feces are dry and mixed with peat moss, even if it does open up, it is relatively innocuous.

Total cost?  Under $300, plus shipping.

A final word since we are on the subject, and that is toilet paper (TP). You can use Mullein leaves, but let’s not stress the ladies out. Simply this, the healthier your gut the less TP you will need.  If you have a good diet and gut, one wipe and you’re done.  If you are going through a lot of TP, then something is off.  Either your diet isn’t working for you, or you need some probiotics.

What’s true for animals is true for humans.  If an animal (or human) soils itself (read: needs a lot of TP) somethings amiss in the intestines.