What happens to the water in the waste?

Food waste is 80% water. After deducting water retained in the final compost, for every 1Kg of food waste added, almost 0.7Kg (0.7 litre) of water has to be removed.

There are two possible options for this in composting:

1. In hot composting (HOTBIN), the heat evaporates the water out as steam vapour.

2. Predominantly in cold composting, the water is allowed to drain under gravity to the base of the bin.

It is very rare to add additional water into the HotBin ; the food, grass and plant waste already contains more than enough. If you think you need to add liquid, have a look at our post for what to do if your waste looks too dry.