Incineration or composting toilet on a narrowboat? Both!

 COMPOSTING V COMBUSTING TOILETS ON A NARROWBOAT

Toilets – that narrowboat conundrum that never really gets resolved. The two main choices seem to be cassette or pump-out, however for braver souls, newer options include composting toilets (increasingly referred to as waterless toilets) and incinerating (or combusting) toilets.  In designing our new narrowboat from scratch, we wanted to handle human waste cleanly and conveniently, with sustainability in mind, without being restricted to traditional narrowboat toilet options

NB Sea Glass is unusual because she has two non-conventional toilets fitted – a Separett composting toilet in a separate cubicle and a Cinderella Motion combusting toilet in the main bathroom. Our hull builders, XR&D of Ollerton, built air inlet vents for the combustion loo, and air outlet vents for the composting loo into the hull design, so installation was easy.  Our boat fitters, Narrowboats of Distinction, had not installed either type of toilet before, but rose to the challenge and enjoyed doing something different when fitting her out.

Here’s our story, how and why we made our toilet decisions, and, six months down the line, what we really think of our choices.

Firstly, we are not against cassette toilets. We’ve had a motorhome with a Thetford cassette toilet for nearly 20 years, are used to its features and are happy with it. It’s certainly far better that the “bucket and chuck-it” on our first GRP cruiser in the late 1980’s – just a toilet seat and lid on a bucket!

Our issue with cassette toilets on the canal network (from our hire boat experience) is being tied to cruising between Elsan points. If you want to linger somewhere for a week or two, are not near an emptying point and you reach full toilet capacity, you have to move. Even with two spare cassettes, you only have a few days usage, depending how many are on board. Other “against” factors include storing full cassettes on board and having to empty several cassettes at once. Furthermore, cassettes are heavy when full, awkward to empty and Elsan points often smell extremely unpleasant

Pump-out toilets are a different matter and we really dislike them. We’ve had off-putting experiences on hire boats – a continual lingering smell in the bathroom, using fresh water to flush then paying to have it pumped out, the tank filling quickly with four people on board, finding a pump-out station when almost full, arriving to find pump-out broken, panic setting in . . . . . . (I have a phobia about a toilet getting full and nowhere to empty it)

These are the toilets we had installed, and our experiences using them

Our Separett Villa 9010 composting toilet

We chose the Separatt Villa because it looks like a “proper” toilet and aesthetics were important to us. It doesn’t have a stirrer to mix the solids content around, so emptying does not involve having to shovel out part-composted material. It is slightly larger than a Thetford, but we designed this in to the toilet cubicle.

A composting toilet is a sustainable option for a narrowboat. The initial price can be high (we paid around £750 for our Separett), but ongoing costs and maintenance are minimal. You can build your own composting toilet for much less, if that is your choice, and there are plenty of online groups which can assist with that option. It wasn’t for us.

Consumables include a liner for the toilet bowl, cover material for solids – coir, sawdust, cat litter, wood shavings – whatever you find works best for you, and something to spray the urine separator to keep it fresh after use – we use a spray bottle and make a mix of white vinegar, water and lavender essential oil. So once installed, this type of loo is cheap to run.

 

A potential disadvantage of the Separett is having a remote urine tank, as there is no integral tank like most other waterless toilets. This wasn’t a problem as we designed and installed a 20 litre stainless steel tank which XR&D Boat Builders made as part of the hull infrastructure. This sits hidden under the bunk in the adjacent bedroom.  It has an integral gulper pump for emptying and is removeable for maintenance and cleaning (and we had to do just that after only a few weeks – see later).

Advantages of this type of tank are several days capacity before the urine needs emptying (depending how many people on board and how often you use the loo), no visible urine tank, and emptying is easy.  Our Digital Boat Management System tells us when the tank is getting full, so no accidental liquid overspills!

Emptying the urine tank is done with an electric pump which pumps liquids into a 20 litre black waste tank. A key is inserted into a lock near the toilet before pumping can commence, to prevent accidental discharge of liquids into the toilet cubicle. The tank is emptied at an Elsan point if we are near one, or stored in the gas locker until we are. 

After pumping out the urine, the final task is to flush the tank through with fresh water (via the toilet), which is also pumped into the black waste tank. The whole emptying process takes around five minutes

There is a spare 20 litre black waste tank on board and with the built-in stainless tank, we have around 60 litres urine storage capacity – more than two weeks – giving us plenty of time to find an Elsan point.

Initially we didn’t put anything “deodorising” into the remote urine tank and frankly there was an awful smell throughout the whole boat when emptying the urine. Putting a small amount of Elsan fluid down the loo after emptying solved this problem. Bio washing liquid would probably work instead, but we’ve not tried that yet

In a composting toilet, liquids go forward and solid go back. The Separett has a flap concealing the inside of the toilet bowl and this opens automatically when you sit down. The inner bucket rotates slightly every time you sit down, so no need to stir the contents as is the case with some composting toilets. Everyone must sit to use the loo.  We’ve not had an issue with getting urine in with the solids, because the Separett has a removeable piece of plastic which acts as a deterrent for liquids going back.  I understand if that happens it is not a problem, because the fan and cover material soon dry it up

Ladies wee paper goes into a bin “continental style” and other paper goes into the solids bowl which helps with coverage and absorption. And no – there is no smell from the toilet. The cover material and 12 volt fan see to that.

We are recreational boaters, so at the end of a period on the boat, the bag containing solids and cover material is sealed and brought off the boat – a process which takes around five minutes. We have a large garden and this waste goes onto a “humanure” composting area well away from the house to continue its composting process. If this is not an option, solid waste can be double bagged, marked “Human Waste” and put into CRT rubbish disposal area.

Issues we’ve had with the Separett 9010 Villa

We had just two issues. One was the toilet fan, which caused noise, vibration and was audible at night. This was solved by replacing it with a smaller computer fan and it is now silent. The second issue was the integral pump inside the urine tank failed within a few weeks (this was chosen by us and not the boat fitter). We had to access the urine tank and replace the original submersible bilge pump with an external gulper pump (the same type you have in your shower).  This has worked faultlessly ever since

Our Cinderella Motion Combusting (Incineration) Toilet

NB Sea Glass is one of the first boats in the UK to have this new Cinderella Motion toilet fitted. Created originally for the caravan and motorhome market, they are also suitable for narrowboats and widebeams and have been available for around 18 months

The Motion model is sleek, attractive, modern looking and aesthetically like a compact normal toilet, but without a cistern. It is waterless, odourless and hygienic to use. Ours runs on propane. There is an electric version but this would only be suitable if you were on permanent shoreline

We chose it for ease of use and minimal, almost zero waste products. The two major downsides are the initial purchase price – around £3,500, and the ongoing cost of propane. If you used it for every toilet visit, it would work out expensive to run in gas usage. You must decide whether the convenience outweighs the cost.  For us it does. However, because we have an alternative toilet, we are not using the Cinderella as much as if it was the only loo, therefore our gas usage is much lower

Day to day, we use the Cinderella mainly (but not exclusively) for solids, and the Separett for liquids. It depends how many people we have on board (we can have up to six) and what the queue for the loo is like.

Open the toilet lid of the Cinderella, and inside is a stainless steel bowl, angled downwards, with an electrically operated trap door, which only opens with the lid closed and the “flush” button is pressed

Before use, the bowl is lined with a made-for-purpose waterproof liner (it looks like greaseproof paper). Putting the seat down holds the liner in place. As soon as the lid is lifted, a fan starts, which sucks ALL smells out through the chimney. No need for air freshener with a Cinderella!  All liquids and solids go into the liner, which is then folded over and twisted to contain the contents. To “flush”, the lid is closed, the “flush” button is pressed, you hear the trap door open and close, and the combustion process begins.

Up to four people can use the toilet (one after each other). You do not have to wait for an incineration process to finish. The contents are just added to the combustion chamber and the processing time is extended. The combustion process takes around 40 minutes, longer if more than one person has used the loo

After around 70 “flushes” a red warning light flashes alternatively with the amber “combustion in process” light on the control panel. There are around 30 more uses before you must empty the ashcan. We always empty at this stage, otherwise the red warning light flashes and an alarm sounds every time the loo is used, which can be a bit worrying.

To empty the ashcan, the toilet hinges up quickly and easily and stays in place whilst the ashcan slides out and is removed for emptying.

The ash is sterile and is disposed of the same way you would with your wood burning stove ash.  We tip it out onto newspaper, wrap it up and put it in with our general rubbish. It could however be emptied under a hedge.  It is good practice to brush any remaining ash out with a stiff brush to make sure no ash remains, before replacing the ashcan and clicking the toilet back down into place

Issues we’ve had with the Cinderella

As early adopters of this new-to-the-market toilet, we accepted there may be initial teething troubles. These were our issues and how we resolved them:

1.    Our Motion repeatedly went into error on first use. We cleared the fault and used the loo, but it was worrying as we didn’t know what was causing it. It turned out to be an error with an internal sensor which hadn’t been properly set at the factory before despatch. The supplier came out to the boat and quickly fixed it at no charge

2.    Voltage drop. The toilet needs a minimum of 10.5 volts to operate.  If the voltage at the toilet drops below that, the toilet goes into error (which is easily cleared). To resolve this, we replaced the original 2 mm electric cable with 4 mm cable. This cable was sized by the loom manufacturer based on Cinderella’s power requirements. However, it was a voltage drop due to the length of cable from the batteries to the toilet, which caused the issue.  So depending how far your toilet is from your batteries, you too may need to specify 4 mm cable

3.    The toilet needs to cool down after use and before switching off power to the boat The fan needs to keep running well after the combustion process, and if you are returning to a marina and want to leave the boat, you need to wait for the fan to stop.

4.    In use, the Cinderella is intermittently quite noisy.  After “flushing” you hear an ignition sound as the gas starts burning.  This repeats several times during the burning process. Not a problem during the day, but if your toilet is next to a bedroom and is used at night, it could be quite invasive.

Composting or Combusting?  Our conclusion

We have the best of both worlds and realise we are fortunate to have space for two different toilets. If one doesn’t work for any reason, we have a spare, and that is excellent for peace of mind. We keep propane costs down by using the Separett as described above, so that is not a big issue and we mostly use the Separett during the night, so are not disturbed by ignition noises.

We love the Cinderella and all its advantages, and would definitely choose it again for our boat layout. However, if we only had room for one toilet, we would choose the Separett over the Cinderella for three reasons:

(1) If the Cinderella develops a fault which you can’t resolve, and it’s your only loo, then you really are in trouble. There are several error messages in the manual which say “Call Engineer” and if you are miles from anywhere, that could be a big problem.  There’s little to go wrong with our Separett, apart from the remote pump failing, which can be resolved by manually emptying the tank with a spare pump.

(2) The ongoing cost of propane. If Cinderella could reduce gas usage and therefore running costs, that would be a huge benefit and could make it more attractive and affordable to a wider audience

(3) We feel the Cinderella is a little too noisy if used during the night, but it depends how tolerant you are of noise, and where your bedroom is relative to your toilet. 

Therefore, in our test of the two toilets, the Separett composting toilet wins over the Cinderalla combusting toilet because it is reliable, resilient and reasonable to run

If you have any questions about anything in this article, you can contact us on Twitter: @NBSeaGlass