A well mixed compost pile will also reach higher temperatures which will help destroy weed seeds and pathogens. Adequate moisture is essential for microbial activity. A dry compost pile will not decompose efficiently. If rainfall is limited, it will be necessary to water the pile periodically to maintain a steady decomposition rate. Enough water should be added to completely moisten the pile, but overwatering should be avoided.
Excess water can lead to anaerobic conditions.
Water the pile so that it is damp, but does not remain soggy. The compost will be within the right moisture range if a few drops of water can be squeezed from a handful of material. If no water can be squeezed out, the material is too dry. If water gushes from your hand, it is too wet. Smaller particles have much more surface area that can be attacked by microbes.