All life on this planet needs water. Monitoring your compost moisture is vital to the billions of living decomposers who are calling your compost home.
The ideal moisture level for compost is between 40% and 60%. In practical terms this feels like a sponge that you've squeezed most of the water out of. At this level there is a thin film of water covering all the soil and compost particles.
It's worth remembering that most of the food scraps and other greens or nitrogen rich material are quite wet. The other day I left a few mung bean sprouts on the counter. The next day they had almost shrivelled right out of existence. These greens generally have about 80-85% moisture levels. When you mix them with the dry, brown, carbon rich material they will soak up some of the excess moisture. However, you may need to wet down the dry brown material somewhat as you add it to the compost.
The problem with compost moisture levels above 60% is that the water starts to displace the air in your compost. This can create anaerobic conditions in the pile.
You'll know your moisture level is too high if your compost starts stinking. Anaerobic conditions smell like rotten eggs or ammonia. To lower your compost moisture levels try one or more of these strategies:
When the moisture levels fall below 40% decomposition will start to slow down. Below 15% and decomposition stops and I suppose mummification begins.
Here, in Southern Alberta it is pretty darn dry. In fact most compost problems here come from overly dry conditions. In dry areas or in drought years you might try some of the following strategies to keep compost moisture levels up: