DIY Composting Toilet- The Petersen Family in an Airstream, 5th wheel and Tiny House

What made you decide on a composting toilet? 

I first learned of the composting toilet solution from the airforums online. Several individuals had reported good results from manufactured composting toilets made for sailboat applications. I was intrigued by this option. I am a gardener and all about composting so I looked more into this option.

In the US we have an interesting relationship with our waste, namely that we have neat and tidy ways of simply making our undesirables disappear. We are so isolated from our waste because we have engineered ways to haul or flush it away.

Even though we may be oblivious to what happens after we flush the toilet or the garbage truck hauls our bags away, the fact is the way we choose to handle our waste is irresponsible and poor for the environment.

The best option for our Airstream, and the most responsible, was a composting toilet. (As a side note I am happy we won’t be hauling around a tank of chemical laden smelly waste. I have yet to visit an RV that didn’t have that poop+chemical smell!) This option avoids adding a new tank and frees up our existing tank to be used for gray water.

What made you decide on a DIY composting toilet solution? 

After pricing out manufactured units we decided against buying a premade option. (The cheap version is over $800.) These units are bulky and didn’t flow with our bathroom layout. They are pretty simple so we decided to custom-make a composting potty. Basically all you need is a receptacle (5 gallon bucket) and a toilet seat, plus a diverter if you want to add that. 

There are two camps around composting toilets and making humanure. One says put all the waste in a single bucket then cover appropriately (Jenkins’ one bucket method) and the other says separate the #1 and #2 with a urine diverting toilet seat. 

We went without a diverter for our first toilet, and then added one for our second prototype in the 5th wheel. 

How did using a composting toilet work out for a family of four? 

One 5-gallon bucket will last our family almost 2 weeks with regular use (without a diverter). We use other facilities when available and use the composting toilet when other facilities are not convenient or available.

We keep our bulk supply of covering in our garage (inside the bed of our truck). It can be a hassle to run out to the truck to fill up our covering bucket. The few times had smell issues was due to running out of material in our covering bucket.

When the bucket is full we simply add it to our compost piles and cover it with other food scraps and grass clippings, leaves, and any other organic material on-hand. With compost, the trick is to manage the nitrogen to carbon ratio while keeping it semi-moist. Before adding a new bucket to the pile, we make a small well, add the bucket, then cover with new grass clippings. We add water to the pile if needed. Worms have overtaken the pile and its amazing how fast it breaks down! As long as the pile is not too wet and covered, there is no smell or flies from the pile.

We invested in a kiddy seat for our little ones to make using the composting toilet easier for them when they were smaller. 

You decided to switch over to a diverter after a couple of months. Why?

I made a diverter to increase our solids capacity. The bucket filled much quicker with both liquids and solids and I was hauling around buckets in the back of my truck. The liquids I could easily empty. The solids were much harder.

I had 6 buckets travel with us in the back of the truck, which would hold us over for a few months if we used a diverter. They were then dropped off and composted on a family property whenever we came by.