Composting toilets

Hi, Wondering if anyone has these & which ones they would recommend please?
Will be building house soon & heard on ABC radio talkback show how good they are now, but there is heaps of different ones.



Having considered such I rejected the idea at the time because:

  • They require special construction to instal which isn’t cheap
  • All the models my friends had smelled. They work best in a very dry climate.
  • Eventually they need to be dug out, who is going to do it?
  • Those with fans need power.
  • There are plenty of easier ways to save water
  • You can get back the water that goes down the loo if you are not on sewer. If you are on sewer are they permitted? (Dunno)

If you are in a desert (I am not) where every drop of water counts they might be worthwhile.

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Welcome to the community @Jenny13.

Can we assume that you have confirmed with the local council that you will be permitted to install a composting toilet system at your site?

Have you considered how you are going to treat and manage the grey water, assuming you do not have access to a reticulated sewage system?

Our local council assesses requires a professional hydrology assessment and design for properties that are not able to be connected to reticulated services. The professionals determine what is suitable and able to meet council requirements.

Assuming you are able to install a composting toilet system, the service you engage should also clarify which types of design will meet with approval. They may also be able to provide references to other locals with similar systems that have been successfully installed.

(Edit) One type of system all above ground.


I installed a Clivus Multrum CM8 here when building my house 10 years ago. The Clivus Multrum has approval in most local council areas AFAIK.

To address these now numbered points
1/ No special construction required- they go under the floor and you only need to cut a hole in the floor with a jigsaw, a 10 minute operation. Depending on clearance, you may need to dig a bit of a hole to accommodate the tank

2/ The only time I get smells if if spider webs clog up the vent chimney, which is fixed with a brush on a length of wood, another 10 minute operation a couple of times per year. Both my wife and I know for certain that ours smells much less than most regular water wasting toilets. Any fumes are sucked away instantly by the fan, no fart smells in the room!

Dry or wet climate does not matter, it doesn’t rain into the tank. They do work best in warm climates, bacterial activity slows significantly when the pile temp goes below 13C, which does happen here over winter, meaning the pile doesn’t reduce in size as quickly. Luckily we have an army of slaters in the tank, and they do a great job of breaking the contents down, even in winter.

3/ I’m ‘chief sh1t stirrer’ here, which involves using a hoe to move the contents around a bit, a few times per year, you guessed it, another 10min or less operation. Once or twice per year I need to shovel out the composted material and barrow it away, usually to be spread around our fruit and nut trees.
That does take more than 10 mins, probably 30-60 mins, as the trees are some distance away.

4/ Yes the fan needs power, ours uses a massive 0.1kWh per day.

5/ Water is in short supply here, this is the best way to save a lot of water.

Clivus also supply treatment tanks for greywater systems. I had to dig a 20m long absorption trench across the hillside with a poly arch covered by geotextile and gravel, then covered with soil.

6/ We planted some clumping bamboo just down slope from it to take advantage of the water from showers, washing etc.


Thanks Mark no haven’t done any of that will have to write a check list


Hi Gordon, are you happy your Clivus Multrum CM8?

We’ll be building between Kemspey & South West Rocks, NSW so will be reasonably warm


Yes Jenny13, very happy with it! Quite easy to install and set up, and ongoing occasional sh1t stirring and compost shovelling is not really that big an issue. The water savings are invaluable when you only have rainwater collected from the roof.

Re council approvals,

The CM8 is certified to Australian & New Zealand Standard 1546.2:2008 and is approved in QLD, NSW, VIC, ACT, NT, SA, WA and TAS (The products are approved only if installed as per the installation manual).

A local council has to approve it being installed, unless there are issues with greywater discharge near a local waterway.
Have a read of all the useful info on their website:

Disclaimer: I do not get paid by them, I’m just happy with their product.


Thanks for that Gordon


The climate determines how well the moisture evaporates, dependent on the ambient humidity, not rainwater getting into the tank. Do you mind saying approximately where you are?

We could spend some time on what is “a lot”. Would you accept that the water that can be saved by altering flushing habits from the typical town water situation and by reusing grey water or treated water both exceed the minimum flushing required that can be saved by the composter?

If you have your own treatment plant you can reuse all your shower, washing, washing up and flushing water.

Inland NSW, average rainfall 750mm/year, annual average temperature now ~18C, and gradually increasing.
It is certainly dry enough in 99% of Australia for evaporation to be sufficient for composting toilets to work.

Mixing perfectly good drinking water with poo then flushing down the loo is a waste, with home treatment systems it can never be used in the house again, so reusing has serious limitations vs not using it to flush poo in the first place.


Currently Bridgewater Vic, with only rainwater & off grid power. Land at Clybucca that we’re going to build on. Has to be 2 storey as land floods. Will also have off grid power - a lot cheaper than getting it connected there.
After hearing about the toilets on ABC other morning decided has to be the way to go. Also think we should be using our grey water, which we don’t here. We will have town water there but intend putting in rain water tanks for house


All of that is true. But you are not supposed to use any reuse water in the house, whether grey or any other colour, we are talking about the garden.

The question is compared to reducing the waste from flushing to a minimum is it really worth the trouble of having a second disposal system to save the residual amount?

In my case our daily water use is about 150 l, of that about 10% is toilet flushing. To me the objective was to get usage down from city levels like 400 l /day and to reuse 90% in the garden.

To have a composter my house slab would need to be raised (at considerable expense) at construction or I would need to have a pit below the toilet which would be at risk of filling up with water or if lined floating, as I do get heavy downpours and have clay soil. If retrofitting the pit or an elevated dunny are the only options. Then there is the cost of the installation and its power supply and the quite small running cost. You don’t seem to mind the shovelling, I can deal with chooks, horses etc and having changed the odd nappy I know that one little touch is not a death sentence. Even so it is a chore I can do without.

So if I had a composter, assuming it worked as well as yours in my much more humid district, my tanks would last 330 days instead of 300. It just is not worth it to me.

Admirable and practical.

Our house site is partly on the overflow - flood plain of one of the local creeks. The house needed to be built on the one spot that was not subject to inundation from a 100 year flood. That included the sewage tank, black and grey water trenches. It all fails miserably with the future mapped flood levels assuming the more extreme impacts of global warming. In that instance the flood line comes up to the bottom of the front steps and every house stump.

Hopefully your circumstances with Kempsey Local Council are not that dire. At least with a composting system if you can install above flood level it should still function while you are water bound. The council responsibility for our area has changed three times in 25 years. The first very farm orientated of the three was far more relaxed in the 1980’s about approvals than today’s urbanised development fee collecting upgrade.

We have a hydrology and professional plumbing report to upgrade the existing septic system, assuming council approves it. Just to add an extra pedestal without adding any extra bedrooms or occupants! The neighbours who have dared ask have all been directed to install expensive AWS, no alternatives considered.

I’ll suggest that given the option of a septic or a composting system the latter produces a better outcome environmentally without the worry of tree roots etc blocking the absorption trenches. Alternately fencing off a surface transpiration area on land that has flood flows seems high risk and adds nutrients where the desired outcome may be less.

We are not legally permitted to utilise the waste from any system, including composting systems to fertilise or water edible produce. Observance and common practice sometimes differ. For Kempsey Shire refer:
On tank water only!
With two we consume approx 6,000lpm or 200lpd including pot plants and the seedlings in the garden nursery area. Dual flush low volume toilet.


thanks for your insights Mark