Grey water is what comes out of the sink and the shower (soapy, with food scraps and grease), as distinct from the "black water" of the chemical toilet. It's the tank that gets neglected most and, ironically, the one that causes the most smell problems. Managing it well is simple and, above all, a matter of responsibility towards your surroundings. Here's how.
What it is and why it smells
Grey water builds up food scraps, grease and soap. If it sits in the tank for days, it ferments and generates bad smells that rise up through the sink drain. The "rotten egg" or foul smell usually comes from a neglected grey water tank, not the toilet.
How to manage it properly
- Empty it only at designated points: motorhome aires have specific grey water drains. Never tip it into nature, ditches or drains not designed for it.
- Don't let it build up: empty it often so it doesn't ferment.
- Filter out food scraps: use a strainer in the sink so scraps don't reach the tank.
- Mind what you pour down: use biodegradable soaps; the water can end up in the environment.
How to prevent and remove smells
- Clean the tank periodically: water with a little vinegar or dedicated products, sloshed around while driving.
- Leave some clean water in after emptying so scraps don't dry out.
- For long storage, leave the tank empty and the cap open so it can air.
Responsibility: everyone's image
Emptying grey water where you shouldn't is one of the behaviours that most damages the image of the camper world and prompts bans on overnight parking. Doing it properly isn't only about hygiene: it's about protecting everyone's continued access to enjoy these places (see sustainable camper travel).
In short
Grey water is the soapy water from the sink and shower; it smells if it builds up, and should only be emptied at designated points. The step you can take today: get into the habit of emptying it often at aires, using biodegradable soap and cleaning the tank now and then with water and vinegar; you'll keep the smells at bay and protect the environment and everyone's image. Combine it with the maintenance checklist.