How Does a Composting Toilet Work ?

DIY composting toilet (for our “dream” future mattress showroom) is in! 

Because of the size of this houseboat, a marine toilet/head is required onboard by the Coastguard so I DIY’ed a composting toilet using only materials I had on hand and I am very surprised how well it works!   

So, how much money does a composting toilet cost?  Ready made composting toilets cost too much in my opinion for such a simple thing.  My cost was actually $0.00, as all the materials I used were100% up cycled for this DIY composting toilet design!  

This is the best composting toilet because you can try different things and add the features you need.  See the list of materials I started with below. 

I will eventually make it more pretty, but this is the testing phase.

So the basic design of a compost toilet is separate (strategically placed) holding tanks for the number 1 and number 2.  

A funnel, up front, catches the #1 and a ping pong ball stops the air and smells inside the container from escaping but it also floats to let the liquid go in. Got this idea online, brilliant how well it works with zero smell so far and super easy to keep clean.

The compartment for the less used #2 compartment is an upcycled diaper genie (I used an Ubbi scored on Freecycle as it has a sliding door you can easily open and close, all steel and has a ring to hold a large biodegradable bag which I will have to purchase, so yep, there will be a small cost).

There is a larger removable funnel that gets a paper liner to make sure everything gets into the right spot since this toilet uses no water (scary, I know). Once you do your business, simply pour in some compost starter and plant material to cover everything and let the composting begin!

To empty just remove the bag and dump into a designated compost area and use for flower gardening, not for your veggie garden.

I have had luck composting my food waste in an anaerobic environment using EM1 (aka Bokashi) but time will tell on how well it will work for this application.

Plan B, if things don't break down fast enough, will be to add 2 air vents with a solar-powered fan that will constantly draw the air in from the room, through the diaper gene and then vent out to the outside. Keeping things dry is key, so I do expect to do this step eventually.

Anyway, this is something I have had on my life buck to-do list so it feels good to have it marked off as accomplished (for now :) and I look forward to making any improvements needed as things “go” (pun intended).

After further testing, I would be happy to post more details of the construction / process if anyone is interested.

Materials used so far:

Tall old wood storage bin

Toilet seat from the old, non-working toilet / head on the boat

High quality closed cell foam packing material from our turntable - 2 pieces

2 pieces of heavy duty Velcro to attach toilet seat to foam

2 scraps of wood to support the toilet seat / foam combination

Dishwashing liquid bottle, cut into a funnel

Ping pong ball

Large (empty) glass wine jug with screw on top removed but kept on hand

Plastic tube (about 5 ") taped with electrical tape to the bottom of funnel

Ubbi diaper genie - steel with sliding door and odor gaskets


Biodegradable plastic bags 

Large paper coffee filters with center ring cut out 

Toilet paper

Hand sanitizer 

Poo Pourri spray 






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