In the course of the biological process of degradation, water is decreased in the compost windrow. However, to achieve a successful composting a minimum water content is necessary to avoid dry stabilisation. Dependent on the initial humidity of the material, it will be necessary at some point in time to irrigate within the composting process. The irrigation system should be fully automated and not required manual input. COMPOrain helps to pilot irrigation valves individually for every line. This way the required minimum humidity content can be achieved. COMPOrain will control the irrigation time and the amount of water irrigated on each pile. This system is fully automated and documented by the computer.