This project undertakes a review of the systems and practices used in this hydroponic lettuce sector in order to shed light on this issue and help tailor future research and development towards a solution. The review includes a scientific literature, previous and existing lettuce projects and interviews with growers and others involved in the industry. This will seek to highlight the reasons for pesticide residues in hydroponic lettuce exceeding the maximum residue limit, from this project recommendations and existing guidelines for the use of pesticides in hydroponic lettuce systems will be modified accordingly.