Composting Toilets

The information below has been kindly provided by liveaboard narrowboat owner Allan Cazely. It’s additional information on the subject which many narrowboat owners are obsessed with. I wrote briefly about the subject in this post several years ago.

Composting v Other Types of Toilet

I have read a couple of issues regarding fitting out of a wide beam boat. One issue took on board the always popular subject of toilets.  In this case a Composting Toilet was chosen I would like to expand on Composting Toilets, as I have had one, (Self Installed), on my boat since it met the water over 8-years ago. They are not as attractive and simple as one would be led to believe!  They are excellent when you learn about them.  In the first couple of years, I struggled with my Canadian “Envirolet” and nearly decided on changing it for something else.  However, today, I wouldn’t change it to a different type of toilet, as it is so flexible and to date, never so overfull that it cannot be used.  From this angle, it beats all other toilet methods –

Holding Tanks – Gravity Type Toilet

Holding tanks have to be emptied as soon as they are full, The “Dump Through” type that depends on gravity, where the bowl sits over one end of the tank in the loo, whilst the other end is usually under the double bed, is quite popular. However, when the tank is full, the bowl will not empty and your loo cannot be used until the tank is emptied.

Vacu-Flush Electric Toilets

If you have a Vacu-Flush type of toilet, it is possible to carry on using it when the tank indicator shows full, overfilling the holding tank.  This has shed loads of problems, if this happens.  The effluent then goes up the vent pipe, as it can only go in that direction, and then the effluent then exits through the fine gauze, (That stops the flies getting in).  This then becomes blocked and the tank will pressurise!

In severe cases, the tank can split and the boat ends up floating in effluent. This is a rare occurrence but can happen. If the tank is pressurised, there is then the problem of emptying the tank.  As soon as one takes the screw caps tops off the discharge pipe, (Or the water flush a smaller pipe outlet), the effluent shoots into the air just like a burst main water pipe.  I have experienced this syndrome with my friend’s boat on the last pump out. The fountain of effluent lasted about 4-minutes and was quite spectacular! I was covered in the stuff and as soon as possible I had a bath and a complete replacement of everything I was wearing, plus washing my hair about 3- times, before I felt clean again.  The old clothes went straight into the washing machine for; first a rinse and spin, then a full wash program.

Cassette Toilets Types

Cassette types of toilet need to be emptied about every 3 or 4 days. With extra cassettes, visits to the sani-stations can be extended
So now you have to decide on your preference of loo types.

Composting Types of Toilet

These are invariably an “All-in One” Unit, usually free standing, like the Cassette types. There are basically 2 types of composting loos put into boats. The earlier types had one holding area for solids and liquid and depended on the liquids evaporating, leaving the solids to decompose.

In the UK, the relative humidity is too high and evaporation fails to take place.  In almost all cases, this is the cause of ongoing problems that cannot be solved. People try and heat the casing to encourage evaporation, but it is rarely successful.  This is my personal experience with my Envirolet. (This had a 220-vac heating element). This needs my engine to be run all day long to cope with the energy used – OK if you are hooked up to a land supply – Still expensive to run though!

In the last few years, modified composting toilets have appeared on the market.  These have 2-compatrtments, one for the solids, and one for the fluid effluent. This is usually successful in this Country and doesn’t need additional (Expensive) energy. These toilets are still simple and uncomplicated. The only difference being that the bowl is so designed that urine is filtered in a funnel into a removable tank.  Urine is sterile and can easily be disposed of, almost anywhere.  In the case of my “Envirolet”, I modified an existing removable bowl and modified it to separate the liquid and solids.

The solids stay in my toilet, as before, and the “Rake” and “Spreader” bar handles are used just the same.  I was able to use a flexible polythene pipe, of suitable diameter, to pass through the front of the box, into a 5-litre substantial canister and this is easily emptied. It can be screw topped and put one side for later disposal (Sani-station or suitable field).

Since making this modification to my boat, I have found my toilet easy to maintain and easy to empty.  All the solids are dry and friable with absolutely no unpleasant aromas.  Now that I have learned from experience, any fly infestation, (Yes, it does happen in hot weather sometimes), Can be dealt with easily and quickly.

If one wants a summary and personal opinion, I would think that a composting toilet is more popular with male boaters, than female boaters.  The main reason being that one can see the solids at the point of use, when the bowl flap is opened and some females would not like the thought of emptying the composted, dry mass.  I need to “Service” my boat about three time per year.  This suits me fine. I do empty my fluid waste probably on a weekly basis. That’s simple and quick. My toilet doesn’t cost me any emptying costs, unlike pump-outs, either.

It has the convenience of only emptying the solids 3 or 4 times a year and unlike cassette types, I do not have to find a Sani-station either The later types of 2-part composting toilets start at around £500 upwards.