Present crop production in Poland depends on climatic, hydrologic, pedologic, social and economic conditions. Drip irrigation systems will play a significant role in the future by fulfilling the requirements of intensive, energy-saving agricultural production. The total area under micro-irrigation in Poland is estimated to be approximately 3000 ha. Drip irrigation is currently applied mainly in orchards, vegetable farms and greenhouses. The investigations of drip irrigation have shown a high influence of the operating conditions on the reliability and productivity effects of the irrigation system. This paper contains the results of the investigations on the reliability of drip irrigation systems under different operation conditions such as system components, crops, water quality, fertigation and irrigation technology.