Self Containment Certification
Certified self-contained vehicles must meet the Caravan Self Containment Certification standard.
You'll need to be able to live in it for three days without getting more water or dumping waste. It must have:
fresh water storage
waste water storage, and
a rubbish bin with a lid.
These rules are in place to encourage campers to be responsible for all their own waste, and leave each camping area as they find it.
A plumber, gasfitter or other qualified officer needs to check if your vehicle meets the requirements. If it passes, they will give you a warrant and a blue and white sticker to display in your vehicle. These are the only people you should get this sticker from.
More information on self-containment standards.