Ok, let’s get good and awkward because sometimes we have to confront our shit. In our case, quite literally when our Lavac head broke the day we left the marina. We spent a few weeks trekking from the town quay to a local coffee shop to use the loo, but the inconvenience and discomfort forced us to address an urgent waste management issue. Even before we bought Simplicity and started the Sustainable Sailing adventure I knew I wanted a composting toilet. It just seemed so insane to me the we use one of our most precious resources, water, to flush away another extremely valuable resource, humanure. So when living on a boat evolved into creating an eco-ship, I knew that replacing the head was one of our first tasks and even budgeted for it in my initial calculations.

The reasons for going composting are many:

• The simplicity of the design means there is very little that can break.
• There is very little maintenance.
• The is little or no smell.
• They are better for the environment.
• When we decide to stay somewhere a little longer, we will have ready made humanure for ground soil enrichment.

My initial designs were rather ambitious; automatic “flushing systems”, special dropped solids container, liquids plumbing and double fan vent systems. Though with our Lavac toilet broken, those grand ideas gave way to necessity and my design was significantly simplified.

We use a big red bin on our aft deck for composting kitchen scraps. It takes almost two months to fill, so I wanted to use something similar for the toilet. The problem was this would make it too high and awkward to use. I spent hours thinking about the optimum seating position for taking a dump, every time I went to the john I’d note the position and the comfort it allowed, whether different positions meant less wiping due to a better seperation of butt cheeks and where exactly the deposit would plop in the collection vessel. Then I walked past the local trash bin and saw a 15kg vegetable shortening tub, which made for the perfect solids container. At almost the exact height of the Lavac, with a lid and handle to make dumping out more pleasant and it happened to fit perfectly in the space of the old loo.  For the liquids, a 5L water bottle fit the bill perfectly. We’d already been using it as our pee jug whilst the toilet was out of order. This also made us realize just how much we pee. Between the two of us, the 5l bottle is filled in about three days. I didn’t want to have move the bottle this often, so brought some complexity of my original design back and added a pump to drain the liquids out the original intake through-hull for the Lavac.   This was done by adding two plastic taps with tubes leading in and out of the liquids bottle. If needed I can close both taps and remove the tubes to dump the contents. This also allows me to shut off the drain to the through-hull, a requirement in some countries such as Turkey which require a blue card. Perhaps the most difficult part to source was the pee funnel. We first tried a small funnel, like one would use for pouring petrol or diesel, though turns out women pee a lot more vertically than I thought and the funnel did not capture all the liquids so needed to be extended backwards. Finally, we settled on a simple solution. The cut-off top of a 5l water bottle with a tube epoxied into the lid. Perfect size and didn’t cost anything either.

With the the basic design and components sorted, I took to building the housing. Since I wanted to use reclaimed materials, I found an old pallet from a local gardening store, broke it down and sanded it before painting it with 3 layers of varnish and stain (to add some colour). Designing this housing was surprisingly taxing on the brain and definitely the most difficult thing to visualize about the whole project. Drawing pictures helps a lot and I’d recommend to anyone working on a similar project to get out the pen and paper, sit in front of your existing toilet and just sketch for awhile. The design I ended up going with was a box that opened on top to reveal the toilet seat, toilet paper bin and cover bin and a door in the front for access to the solids bin.
The housing sits in the same spot as the old Lavac. The two holes in the bulk head where the old plumbing was became exhaust vents for an old 12v computer fan to suck out air. This vents into the cockpit locker, which has a vent out the starboard side. The fan runs permanently, it only draws 0.3A so it’s barely noticeable. We will see how long it lasts, considering that it was free from the local computer store.

For our first couple weeks with the new head we used spent coffee grounds and sawdust as cover which I collected from the local woodwork shop for free. We lined the solids bucket with a bin liner to make it easier to dump when needed. This has the added advantage of allowing you to turn the solids by lifting the bag up and down, which will compress them making room for more deposits. With the sawdust/coffee as cover, there was a freshly cut wood smell with a hint of morning coffee, which turned slightly sweet as the composting process got underway. Not unpleasant, and certainly nothing like the raw sewage smell we’d been living with after the black water tank sprung a leak. Most days, the smell was overpowered by the local landfill, which wafts into the marina and the town quay in Lefkas, Greece. It took two weeks to fill up the solids bucket and dumping it out was a simple matter of opening the front compartment, removing the bag and rowing ashore to find somewhere to bury the contents.

We have since moved to using cococoir as cover. It comes in compressed bricks which are easy to store and cover deposits leaving no smell. We have also since changed to composting bags, which means we can just bury the entire bag once full and it would compost away, giving its nutrient rich contents back to the soil.

Lessons learned on this project:

• Measurements. Always measure exactly and if you are going to paint after you have cut then remember that the varnish or paint will add a few millimeters that could mean the difference between a perfect fit and not fitting at all.
• At some point in your life you are going to have to face your shit head on.  If you can get over the idea of it being waste and start looking at it as something useful, it will make dealing with it a much more pleasant experience. 

Future adjustments and enhancements:

• Depending on how it goes in summer, I might add another fan to blow air into the bathroom to keep a fresh airflow through the room. This should help with the damp from the shower too.
• Add a T into the drain line which can then be piped into a secondary bottle or black water tank once it is repaired. This is actually part of a bigger idea (see the ultimate goal below).
• Increase the size of the tube from the liquids funnel to the holding bottle as currently if too much cover spills into the funnel it is liable to block the tube.
• Inoculate the cover with mushroom, such as almond portabello, spawn so that it will help break down the solids.
• Increase size of both liquids and solids collection containers. Especially for when Shadow, our daughter will start using the head too.

Resources:

Here are some useful resources for those who are looking to take on similar projects.  Even if you are not interested in composting toilets, I highly recommend you read at least the first couple chapters of the Humanure Handbook.  There is a reason so many where too scared to publish it, the information it contains threatens entire industries and will change the way you see our society.

http://www.cruisersforum.com/forums/f115/self-designed-large-capacity-compost-head-104810-4.html   – Cruisers forum post on composting head designs
http://www.cruisersforum.com/forums/f115/composting-toilets-33029.html – Cruisers forum post on composting head designs
https://permies.com/ – Permaculture site and community, a wealth of useful knowledge.

Final Thoughts:

All in all, we are most pleased with our conversion to the composting head. While we are only a few weeks into using it, the design works well and I am sure it will improve with time. The bathroom now has some colour, character and a bench which is great for changing the little one and using when washing or showering. Though the thing that I like the most about it is the feeling I get when using it. I am not sure whether it is the satisfaction I get from knowing I made it or the fact that it is so simple, but it just feels right. To quote from the Humanure Handbook:

This is just the first step in a grander plan, which may take years to accomplish but the seed is there. Eventually I would like to design a system that combines mycoculture and vermicomposting, to facilitate the breakdown of the humanure. With the worm tea and urine being plumed into a holding tank and mixed with fresh water which can be used to irrigate our hydroponic boat garden. 

If this post got you wanting to know more about waste management, you will enjoy the following video.