My compost is too dry
Water it while you turn it, not from the top. Dry compost is hydrophobic. Pour a can over a dusty pile and most of it runs down the outside without wetting the middle at all. Below: what causes compost too dry, how to fix it today, and how to stop it happening again.
Why top-watering fails
Dry organic matter repels water initially. It needs contact time and mixing. Watering a dry pile from above typically wets the top 5cm and the ground underneath, leaving the middle exactly as it was.
The method that works
Fork the pile apart into a second heap, watering each forkful as you go. Tedious, and it is the only reliable way to rewet a large dry pile.
Why it dried out
Too many browns and not enough wet green material.
Too much sun or wind, particularly on small or open piles in summer.
A lid that keeps rain out without anything replacing it.
Related
Balance is covered in browns and greens. Index: compost problems.
Further reading on compost too dry
Independent sources worth reading alongside this page: EPA, Composting at Home · Cornell Waste Management Institute.