The FOCUS PEARL model was parameterized to perform simulations for Plant Protection Product(PPP) emissions from greenhouses to surface water, after application to a tomato crop. A comparisonwith the open field was made in order to investigate how the climatic conditions, which are morecontrolled under greenhouse conditions, influence the PPP emissions to surface water. Although onlya limited number of runs were performed, the results show the existence of two hypotheticalsubstances (subsequently indicated as CC and CC-M) in the water drained from greenhouses, contraryto what is stated in the European council Regulation 1107/2009. The irrigation amounts given duringthe crop cycle and the temperature conditions within the covered structure have an important influenceon PPP’s emission as increasing the irrigation volume and/or decreasing the temperature result inincreased concentrations of CC and CC-M in drainage water whereas the opposite occurs when thetemperature is increased. Flushing the soil at the end of the crop cycle and irrigating with minimumwater excess during the crop cycles, as an alternative to over-irrigation for the entire cultivationperiod, resulted in lower CC and CC-M leaching/drainage. However to generalise these findings,additional runs for other substances and other crops than tomatoes are required.