Cut & paste from another forum:

During our trip to cape york a very strange thing happened. I placed the pottie on the ground, (it hadn't been emptied for 3 days and was packed in the back of the ute), I noticed it was a little wobbly on the ground and the sides seemed a little ballooned, so I lifted the lid, and pulled the slide lever out and boooom, a giant poo explosion. Liquified poo and urine covered my hair, face and body as well as a small amount in my mouth when I gasped. Can anyone explain why this happened. Thanks ____.

According to a number of posts, it has happened to others.

Have done similar ..... but yours sounds a bit worse, I didn't get any in my mouth. I had used too much Sodium percarbonate (napisan) & it was hot weather.

Solution as others suggested:

When fitted into seat unit a valve opens. This valve must be blocked. If in vehicle out of seat unit press in this release valve, much less dramatic.

I always run water through this valve each time I empty, as you found can be an issue if not fully clear.

Another tip:

If there are obvious signs of pressurisation, a Wet One in the bowl before opening the flap/slide is a good idea. and keep the lid closed. Procrastination, mankind's greatest labour saving device!

Acoustic insulation ARB TPMS 3xARB air compressors After cooler Air tank On-board OCD pressure air/water cleaning Additional 50L fuel Carpet in doors ABE 2x1kg Waeco 28L modified fridge Battery 4x26ah Solar 120w Victron MPPT 100/20 DC-DC 18amps 175amp jumper plug Awning 6x255/60R18

open said potty inside the caravan so nothing valuable is damaged, and the surrounding area remains unpolluted.
then swan vesta have cheap simple disposal sticks. At work
At home

"I can't always believe facts I read on the web" - Charles Dickens

winner by default of the tractor vs caravan race

Must have been one hell of a Curry ! ! ! 2013 FL2 XS.
Defender 90 300 TDi.
Defender 90 300 TDi CSW.
1964 MGB Roadster.
1944 Willys MB "Jeep" with bullet holes. (gone)
17 hand Irish Drought Thoroughbred (mostly lame)
Nagging Old Boiler.

Sodium Percolate! Napisan! Surely people should be using the proper chemicals. Might as well use petrol. Everyone can spread it - Anyone can catch it. Stay home - the life you save can be your own!

Sodium Percolate! Napisan = Vanish Oxi Action