I had a composting toilet fitted in January 2019 and at the time, promised to let the forum know, after the first year, how I had got on with it. There is a fair bit to say so I will copy Sir Nibble and post it in sections. (No I won't - it won't let me!)
Views on toilets are very mixed and several bits of this will not meet with complete agreement. All I can say is that I did not go the composting route entirely by choice, it was a decision partly driven by circumstances. This is an honest description of my experience in the last twelve months. I have absolutely no axe to grind here and have no connection with Nature’s Head nor with any toilet supplier.
Background
I have a 70’ Orion tug, built in 2003 and which I have owned since 2013. My wife and I are retired, we don’t live aboard but spend about 7 months of each year on the boat. Our time aboard is split into roughly 6 week spells.
When I bought the boat it had a macerating pump-out toilet and as there was space, I added a 365 Cube porta-potti for emergencies. This arrangement was OK for five years though I never really trusted the pump-out, for one thing, the ‘full’ indicator never worked properly.
Late last year I had a lot of work done on the boat to re-position the engine. As a result I had to get rid of the pump-out toilet, as the holding tank was removed to accommodate the repositioned drive-shaft. I could have replaced it with a cassette but decided to experiment with composting instead.
We bought a new Nature’s Head composting toilet at Crick, Debdale installed it for me as part of the engine move and other work which they did on the boat. The company from which I bought the toilet is no longer in business and I am not sure if Nature’s Head have a UK distributor at present. You can certainly view the toilet on the net and may have to if you want to completely follow what I have to say.
Installation and use
Installation was exactly as per the manufacturers instructions except that the ‘screw down brackets’ which fix the unit to the floor were not used by Debdale and I have not fitted them since. The old porta-potti was not fixed to the floor and I have found no reason to fix the Nature’s Head, in fact it’s simpler to use if not fixed.
A small 12v computer fan extracts air from the toilet and pumps it out through a skin fitting. The fan runs 24/7 when we are on the boat and not at all when we are not. I had planned to use one of the old pump-out exits for this but Debdale preferred to cut a new hole and skin fitting instead.
The manufacture says some substrate should be used and we selected coconut coir. This comes dehydrated in blocks (20cm x 10cm x 5cm) which I buy in bulk from Amazon. I also purchased a number of 30 litre clear polythene boxes from Wilko. These had lids and I cut a large hole in two of the lids, hot-gluing nylon fly screen over the holes. The boxes were intended to hold first the reconstituted coir and ultimately, the ‘product’ while it finished composting.
The boat has an enormous (1700 litre) front deck locker which is of limited use (you can’t easily reach the bottom of it from the deck). It may have been constructed partly for a bow thruster which was never fitted (but who knows, Richard at Orion had some eccentric design ideas). Anyway, my original plan was that I could use part of this locker to stack some of the Wilko boxes - those with fly screen lids - while the ‘compost’ matured.
The Nature’s Head has a horizontal stirring bar about half way up the solid waste container. The manufacturer’s guidance is to start by filling to this level with coir. I prepared the coir by placing two of the blocks in a Wilco box and adding 7 litres of very hot water, putting a (solid) lid on and leaving it for 24 hours. The next day the coir had expanded to about 10 litres and become crumbly, it was slightly moist but not wet.
It takes about 70% of the prepared coir to fill the toilet to the recommended level, I left the remaining coir in the Wilko box which was stored in the engine room.
In use the Nature’s Head requires a little practise, it is very important to keep liquid and solid “deposits” completely separate. So you need to be careful where you are seated on the toilet but it doesn’t take long to get the hang of it. Urine goes into a removable bottle which can be easily changed, we had 3 spare bottles and needed to change one every day. Obviously they are straightforward to empty in an Elsan or even in a public toilet, as there is no mess involved.
The nitty gritty
We find that with only two users we need to empty the solids box every three weeks. Not because the container is full (in fact the level does not change much) but the material becomes denser and the stirrer gets difficult to move.
Here we depart from the manufacturer’s instructions. We decided to do this because the stuff does not smell unpleasant and does not look like a box of turds. The appearance is rather like garden leaf mould and the smell is similar. So we proceed as follows:-
Move the toilet out into the centre of the bathroom
Remove the liquid container
Have an empty Wilco box ready
Trowel out the material using two garden trowels and put it in the Wilco box (*1)
Put new choir in the solids container plus a sprinkling over the solids in the Wilco box
Put the liquids container back, close and replace the toilet
Cover the Wilco box with a fly screen lid and put it in the engine room (*2)
The whole operation takes 10 minutes.
*1 Emptying after 3 weeks results in about 15 litres of waste so you can just fit 6 weeks worth into a single Wilco box.
*2 The original plan was to put the box in the front locker but as there was no smell, we experimented with storing it in the engine room to see if the heat would speed composting.
As we go home roughly every six weeks and only produce a single Wilco box of waste in that time, we just take it home with us and add it to our existing garden composting arrangements. This was a major departure from our original plan but I think we could have managed with the locker.
The difficulty for anyone without ‘hands on’ experience is believing that the quantity of product is so small and that my claims about smell are true. I know, I was surprised myself. Also, of course the system might be unworkable for live-aboard’s with limited locker space - in that respect we have an advantage. But neither of us would go back to the old toilet arrangements and would recommend composting to anyone with the necessary space and an unfussy attitude to getting familiar with their waste.