Including self-containment
 #47397  by kiwibill
 Sat Dec 29, 2012 12:31 pm
I have pm the lady about her composting toilet in her rv but have had no reply,can any one help,thanks.
 #159261  by Travelbuddy
 Thu Feb 27, 2020 1:18 pm
Hi All,
I am in the process of building a new motorhome (truck base) and I'm currently investigating options for the toilet system. I'm very interested in composting toilets for their lower environmental impact and time between empties. I'm planning to live in the vehicle and be fully off-grid.

Not keen on cassettes due to their limited capacity. Also, the use of chemicals doesn't thrill me.
Black tank seems like a much better solution than cassettes, but my understanding is you still need to use chemicals in them.
So....... composting. What's the general opinion?
Are they really that simple to use / empty? Are they really odour free? What ongoing costs are associated with them? It seems some recommend putting 'starter material' in the solids container - is this expensive and how long does it last? Is it easy to source?
The urine containers seem to need emptying every few days. Is this true and if so, where do you empty it? I would have thought you'd kill anything you poured it on?
When it's time to empty the solids, where do you do this? I understand the older solids would have turned to compost but given you'd be using this on a daily basis, surely some of the solids are fresh? How do you manage this? Do you need to take it out of the toilet and store it for a period before disposing?

So many questions! I'd be extremely grateful for any help you can provide. This feels like a really big decision to make all on my own!

Thanks so much
 #159266  by mattn
 Thu Feb 27, 2020 5:05 pm
I would not go down the composting toilet route. They are not not allowed, but they are not explicitly allowed. Where councils have though about them, conditions for their use are onerous for motor homers (e.g Wellington they are allowed, but must dispose of solids on the property the toilet is located and ....). That could all change overnight if too many install them and problems start (and problems will start, because composting toilets need time, care and attention, some people won't give it the the attention the need and take short cuts., Look on the bright side - half composted bags of shit in the bin outside New World will take the pressure of the sliding door campers pooing in the bushes :-T . They are also not a '0 effort' game. They need regular attention and if not done can be smelly and messy, but probably no more effort than it takes to empty cassettes or black tanks.

Liquid is definitely into a sewage system, which practically means a dump station (although some argue urine is sterile so under a tree is fine, reality is urine is not always sterile so is also a biohazard.). Because of this, you need to visit a dump station regularly, so might as well get ride of the solids at the same time. Solids are a bio hazard until fully composted (12Months) , which in most councils are not allowed into household rubbish. Some manage to use a long circular argument starting with nappies and ending into putting the solids into the litter bin outside the fish and chip shop - will get away with it most of the time, maybe even all the time.....

If its just the toilet chemicals you do not like the idea of, Sodium Percarbonate (Nappysan) might be an option. Its cheap, safe and a lot of people use it. Cassette toilet 'capacity' can be extended by adding cassettes - with a new build a locker to store a spare cassette might be a good way to go, otherwise a black tank - but black tanks normally need more water.

Another option is vacuum toilets, I know very little about them though.
 #159267  by David McIntyre
 Thu Feb 27, 2020 7:44 pm
I wondered about disposal.
You can't just pee into a bush, and that is effectively what is being done by emptying the liquid container under a bush/tree.
Not allowed in most public places and NZMCA parks I would have thought.
Interesting about composting the solids, and time taken to ensure they are sterile.
Can't be thrown onto public gardens, so you'd have to use the local council green waste dump.
 #159268  by Derb
 Thu Feb 27, 2020 8:09 pm
Recently we started going through the build/consent process with Otorahanga District Council. The officer I was speaking with suggested I don’t bother going up the composting toilet route as it would not be viewed favourably. This for the reasons Matt has expressed. They are labour intensive and end up attracting complaints from neighboring properties as they seem to be a good idea at the time but many of their owners don’t have the energy or nous to operate them correctly.
 #159355  by Travelbuddy
 Mon Mar 02, 2020 10:30 am
Hmm, it really is confusing isn't it?! It never occurred to me that some councils would not consider it compliant.
So then it's back to black tank by the sounds of it. At least with a black tank you can get many times more storage than with cassettes.
Thanks for the tip re: the nappy san - I'm very keen to be as environmentally low impact as possible.

Question - why do black tanks use more water than cassettes? I wouldn't have thought there'd be a difference.

Thanks heaps for your help everyone!
 #159356  by mattn
 Mon Mar 02, 2020 11:03 am
Cassettes can use very little flush water as the deposits drop though a flap. Black tanks tend to use Marine toilets which need a reasonable volume of flush water. A drop though toilet can save water, you have to use enough flush water so the black tank drains properly and flushes all the solids. Mostly people installing back tanks do so into larger bus or truck based motorhomes, so have carrying capacity for large water tanks, so its not really a problem.
 #159368  by Travelbuddy
 Mon Mar 02, 2020 4:10 pm
Thanks for that.
I've just spent some more time this afternoon ringing some of the NZ suppliers of compost toilets. To be honest, they don't exactly encourage responsible disposal! I can now see why the Councils could be a little nervous of these types of systems.
Maybe I just need to find better non-chemical alternatives for putting in the black tank / cassette. And whilst I was hoping to have to spend less time looking for dump stations, it's probably not THAT bigger deal!
Very much appreciate all the help and support - please do keep it coming!
Thanks heaps and heaps
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