Introducing the Sun-Mar GTG – the perfect portable composting toilet

If you’ve spent any time on boats you will know that toilet systems have come a long way. Even though we’ve grown from sticking our bum over the edge to more sophisticated marine toilet systems, there’s still the issue of putting human waste into our ecosystem.

Why the Sun-Mar GTG is the perfect composting toilet for boats

A marine composting toilet like the Sun-Mar GTG is the perfect solution as solid waste is contained in a collection bin and liquid waste can be diverted into a plastic reservoir for disposal in a non-sensitive environment.

The best part is this boat composting toilet (can be used on motorboats, yachts, houseboats and narrowboats) uses BioBags. BioBags are an ingenious way to store your waste for up to 3-4 weeks. When the chamber is full, you simply remove your BioBag from the container and add it to your compost heap. The BioBag will decompose as it’s made of natural materials.

Sun-Mar GTG – the perfect bathroom companion for a caravan or campervan

We know – we all like to focus on the spacious dining areas or the fully fitted kitchens that many modern caravans have these days. The bathroom is more of a ‘need’ than it is a ‘want’ but we can assure you – when you desperately have to go that need starts to become fairly important.

If you don’t have a properly functioning sanity solution for your caravan, campervan or RV things can get pretty awful very quickly. Here're just a few reasons why a Sun-Mar GTG is perfect for adding to your caravan or campervan:

  • Ultra compact size means it installs in most caravans, campervans, and RVs
  • Runs a low wattage ventilation fan that dehydrates the solids (battery or solar)
  • Can be installed in minutes
  • Doesn’t smell
  • Looks like a normal toilet
  • Has optional urine diversion facility
  • Goes anywhere so you can too

As with all composting toilets for mobile home, caravans, and boats, etc there’s going to be some do’s and donts. These are incredibly straightforward and will more likely have to be told to your visitors.


You can go to the bathroom as usual but instead of flushing, add some organic material like sawdust, damp newspaper, leaves, grass clippings, etc to the top of the pile when you’re done.

You can clean the Sun-Mar GTG like you would any ‘plumbed in toilet’ but it might be worth looking into some more natural alternatives like our Nature Flush Enzyme that not only has a fresh vanilla smell but contains enzymes that will actually help accelerate the composting process of your toilet.

Ladies – if you’re using cotton or natural fibre tampons and pads these will easily breakdown in the composting process.

Blokes – if your prostate is a little dodgey and you get a few weaky leakies, as long as you’re using a natural fibre product to absorb the urine, these can go in the dunny as well!


These are also incredibly simple. Probably the number one rule is ‘don’t put anything in the toilet unless you’ve eaten it first’. Obviously, that doesn’t apply for your covering materials like sawdust, etc.

Don’t let the compost heap get too wet. If your compost pile turns into a slushy mess, there’s a good chance it will smell like a slushy mess!

Buy caravan and boat toilets online

So if you’re in the market for a composting toilet for your boat, RV or caravan, take a look at the Sun-Mar GTG below or go to our composting toilets page.