The composting toilet
Toilets on boats are usually either a pump-out toilet, where the waste is kept in a holding tank until you can pump it out (either by taking it to a marina or waiting until the pump-out boat comes by), or a chemical toilet, where the waste is held in a small cassette which can be taken away to the disposal point. The chemical flush is necessary to keep the odour down.
The boat I bought didn’t have a toilet, so I decided to go for a composting toilet.
I’ve used composting toilets before, at festivals and on camp sites, and they are always so much preferable to chemical toilets. It is much more of a natural process and if they are managed correctly they don’t smell.
Since I made that decision I’ve done a lot of research into toilets, and the results in terms of waste and pollution make scary reading.
A conventional toilet in a house uses an average of 3 litres of water per flush. Unless there’s a grey-water recycling system in place, that’s clean water that we could drink, going into the sewer so we spend time and money cleaning it again. Only 1% of the Earth’s water is drinkable, yet we flush 40% of that literally down the toilet.
A sewage system requires a huge amount of water, chemicals and processes to make our waste environmentally safe. Our sewers are often full of run-off water, oil and grit from the roads, and chemicals from industry and agriculture, which complicates the cleaning process. Yet our human waste has been used for centuries for agriculture as a fertiliser – only in the second half of the 20th century did we stop reusing our waste. Our farming industry spends millions of pounds on artificial fertilisers that contain nitrogen, potassium and phosphorous – the very chemicals that are found in urine! It makes no sense to flush away something that can be so beneficial to us, especially as that then creates a pollutant.
The composting process is a much more natural process. I have a bottle that holds the urine, which I can discard in the bush, and a bucket that holds the poo. After a year or so the ‘humanure’ is safe to be used as a regular fertiliser.
Most people I talk to say, “But doesn’t it smell?”
As long as the contents of the toilet are kept dry, there is no detectable smell – it’s liquid that causes anaerobic bacteria to build up, which is what creates the smell. I dry the contents out by adding sawdust. The bucket itself is open so there is a constant flow of air.
There are many companies that make and sell composting toilets for boats. But that would have set me back around £800, so I made my own.
My toilet is the first thing I show my guests when they come onto the boat. I’m sure they are thrilled.
Building the toilet
Then covered it with a plywood board with a hole cut to one side:
Panelling and a toilet seat are added for comfort and professionalism:
Urine is filtered into an old milk bottle, with the bucket for solids behind.
I love my toilet. It’s comfy, odourless, and I love that it’s natural. I don’t like using normal toilets now – I’d far rather use my own.
The only negative thing is working out what to do with the poo buckets while they mulch down to compost. As a continuous cruiser, I don’t have a set place that I can leave things. It takes about two months to fill a bucket, so by the end of the year I’ll have six buckets of poo sitting around on my boat. The other thing is that small plastic buckets aren’t really conducive to making compost – it needs a bigger space that can drain. So far, I’ve been burying the waste in the woods. Every so often I go back and check on the ‘patch’ – it doesn’t appear to have done any harm. Phew.