Minimizing fouling and scaling problems in RO facilities has been reported as one of the main issues for an affordable desalination for all water types. Fouling can be simply described as an undesirable deposition of deposits in a surface (membrane). In RO systems fouling problems mean higher working pressures, higher energy consumption rates, frequent cleaning and unscheduled plant downtime, making it difficult to comply with contractual water production targets Silica has been reported as one of the most undesirable foulant in membrane systems. Due to a shortage of good quality water in many regions of the world, RO plants are forced to operate with very high levels of silica. Silica chemistry is complex; deposits can be found on the surface of reverse osmosis membranes in a polymeric or crystalline form, and can also reach the membranes as colloidal particles. Traditionally reverse osmosis systems have been operated at low recoveries with frequent cleaning and reduced membrane life as conventional antiscalants are limited in their ability to inhibit silica fouling. Arica Desalination plant, has a capacity of 750 m3/h, and started its operation in 1998. The plant is fed from several wells located at Lluta Valley, characterized by high chloride levels (average concentration over 800 mg/L) and dissolved solids (average concentration over 3.000 mg/L). Feed water quality is variable as the wells have differing geology and chemistry and extraction is dictated by availability not quality. Silica levels in the feed water have increased from the design level of 196 mg/L silica in reject to as high as 300 mg/L of silica in reject. This paper describes the analytical and on-site research work carried out to better characterize factors negatively affecting plant performance. Silica inhibition and cleaning strategies adopted in this plant to minimize the fouling problems identified are explained. The effectiveness of different strategies adopted is reviewed using real operational data available from 1999 to 2011. In this paper cost savings of operational strategies adopted in Arica Desalination plant are calculated and presented. The importance of operational practices in reducing energy consumption is demonstrated. The use of actual silica inhibition and cleaning strategies shows that membrane desalination in very poor quality waters can be a cost effective affordable solution. Results show a significant reduction in cleaning frequency from more than six per year to once per year and reductions in energy consumption of 0.06kWh/m3. © 2012 American Water Works Association.