We have many steps ahead of us before we’re prepared for our goal of hosting tiny house workshops and events on our property. One of the first and most important was to build a bathroom in the area where we park, build, and set up our houses. We tackled it a few weeks ago just in time to test it out by having a big party with over 50 guests, many of whom stayed all day and night – and some into the morning. Here’s how and why we built our compost toilet and how it worked out so far:
Why a compost toilet? We have 50 acres with a one bedroom house on it – we use walkie talkies to communicate with each other on our land. We conduct 75% of our lives 500 yards from the house in a series of huge outdoor rooms collectively referred to as ‘the pond’. As in ‘Honey, when I get home will you be at the pond or at the house?’ It’s where we work, socialize, park our guests, have fires, barbecue, and play. The more people we share these activities with, the more we need a handy bathroom facility. It’s equally obvious that there’s no way we can afford or justify putting in a septic system. Our entire property is a watershed and we don’t want to take any chances polluting, so we wouldn’t even think about doing an old school outhouse, where you just dig a pit and add lime to the cesspool. A waterless compost toilet was the only way to go, allowing us to return the nutrients and organic materials from our waste safely to the soil.
We were on a tight budget and had some materials left over from our tiny house builds, so we opted for an entirely DIY “glorified bucket” approach. I had watched quite a few compost toilet videos over time, and referred back to a couple to help us plan our project. I got the impression urine diversion is the best approach, but to buy a diverter costs about $70 and takes delivery time. Creating our own urine diverter seemed complicated and likely to fail in really unpleasant ways. We always have a large supply of saw dust so we decided to just use larger amounts it to soak up excess liquid and keep put everything in one container for now.
Our general idea was to make a small structure like an outhouse with a bench seat inside. The bench has a hole with a toilet seat and lid over it, and underneath it a bin with a contractor trash bag lining. When it’s 2/3 full of sawdust and deposited material, we’ll open up the exterior hatch to access the bin under the seat, bundle up the bag, and carry it away to our dedicated toilet compost area. We’ll make shallow holes so the bag contents will contact the earth and all its microbes, getting the composting process going quickly. Each bag will be emptied into its own hole so it can rest a full year and add nutrients and organic material to the soil.
Then we raided our stockpile for scrap lumber, plywood, and metal roofing. We decided to make it roughly 4′ x 4′ x 8′ because it seemed like a comfortable size and it minimized cutting. A shed roof was the obvious choice for simplicity, and we decided our left over birch interior ply was perfect for the bench. We gathered up some extra paint samples, and snagged a door purchased for another job that wasn’t used because it had some flaws, but was certainly good enough for our little privy.
Between four and six people were clustered around the project while it was built, although it was so small no more than two could actually be doing anything at any one time. Very little was planned before we started, which was great because it allowed for a lot of standing around debating pros and cons of each step while sipping beer with friends. Nobody got paid in anything but cold ones, and we all enjoyed every bit of it. One guy appointed himself the decorator and made a rustic toilet paper holder, the “sink” (a shelf holding hand wipes), and even a magazine rack.
The one aesthetic touch we knew we wanted was a traditional outhouse crescent moon cutout in the door, so I drew that so it could be traced later with a saw. After the framing was up, we decided to place the door to one side, allowing us to save an extra framing member and leaving a space for something. We all had a sense we should put some sort of window there, but we didn’t think we had anything that would work until I went poking around some old stuff and found a few square acrylic panels. We tried them out, and three of them filled the space nicely, overlapped slightly at the bottom of each for a look reminiscent of an oversize jalousie window.
We left the gables of the shack empty to allow for copious ventilation. At the moment we still have the moon cutout in the door too, but I might put come kind of translucent material in there pretty soon – still looking for the right scrap. Before the party, the guys decided to run a vent stack from under the bench through a hole in the wall and up to the roof. Dylan modified a Studor vent for the top of the stack so that it will keep rain out but always allow air to pass freely.
After we had the shell, we looked for the right container. It had to be strong, durable, and something available commonly, so we could start with two containers and get more if needed that would easily fit through the same hatch. We ended up with a horizontal plastic tub rated for carrying up to 350 pounds of material. It’s way overkill, since lightweight sawdust will always make up a large proportion of the bulk in our batches, but better a stronger container than needed than one that doesn’t quite cut it, for obvious reasons. I would have preferred to use containers with lids, but these tough heavy duty ones didn’t have them, so we went with contractor grade plastic bag liners, which have already been used once or twice before they go to the outhouse.
Dylan painted the exterior a sage tone I mixed from a bunch of our sample colors from recent projects, and my five year old son and I painted the inside a darker tone of the same color. We coated the floor and the door with brick red exterior paint, and one of the guys spray painted the inside of the “window” panels bright red. Last year we had some crafty sessions with a plasma cutter, and cut out a crescent moon from hot rolled steel, which now graces the back wall. Dylan installed and overhead light with an Edison bulb and an automatic shut off light switch, plus a motion sensing porch light outside above the door. A bucket was transformed into a lidded trash container, another bucket became the sawdust bin, and we were ready for prime time. With the same Sierra green roof as my first two houses, and a birch bench with routed edges and a heavy coat of polyurethane on it, this convenience station is prettier than I would have ever imagined.
Our house is quite a walk away up a steep hill from ‘the pond’, so the privy was a welcome addition. We were proud to show our guests to it when the party started in the afternoon, and we got a lot of compliments. By nightfall everyone knew where it was and it was definitely viewed with gratitude and appreciation. Throughout the evening as I conducted my “inspections” the only things I could smell inside were sawdust and a hint of fresh paint. We topped off our bucket of sawdust halfway through the night, and my husband opened the back hatch to check on things and had to shake the container back and forth a few times to settle the pyramid that was forming. One of our guys has a brillant plan for making a teeter totter platform for the bin with a handle projecting upwards. It will allow you to occasionally flip the handle back and forth to shake the bin and settle the contents without having to go outside, open the hatch, or touch the bin.
Today it has been six days since the party, the bin is about half full, and even now inside the privy there’s no odor whatsoever. For us, though admittedly it’s still very early to judge, the compost toilet has been an unqualified success. What experiences have you had with compost toilets? Would you try this in a remote situation like ours?