Sustainable water and energy use for irrigation demands

System approach and sustainable use of water and energy in all kinds of human activities is not required for financial reasons only. It is also a legal and community obligation. The paper deals with the application of Critical Period Method for irrigation system design. Irrigation system includes a Solar Photovoltaic (PV) generator and inverter, a pump station, a water reservoir and pipelines. PV energy is used as energy source for the pump station. Groundwater in combination with rainwater is used for irrigation water demands. This is in accordance with the world and European legislation, directives and strategies related to the negative impacts of climate changes and greenhouse gas emissions.