Reverse osmosis membrane desalination is one of the most significant water treatments that is used to offer freshwater. The aim of this research is to study the effect of controlling the value of the zeta potential on the suspended particles in the water and the proximity of the membrane surfaces in the colloidal solution, to keep the water stable electrically and disperse the colloidal particles. To achieve this aim, the experimental study was conducted in the Sanitary Engineering Laboratory, in the engineering college - University of Baghdad. Two systems were set up, one worked normally and the other worked by using the zeta rod placed before the reverse osmosis membrane. The results showed that the effect of the zeta rod increased all parameters (Total Dissolved Solids (TDS), Electric Conductivity (Ec), Tur., phosphate (pH), chlorine (Cl), calcium (Ca), Sodium (Na), and Fluoride (F)), when compared with the system that worked normally. This effect was due to the added effort of the colloidal particles that saved them in the suspension. This also improved the performance of the reverse osmosis membrane, by increasing the permeate flux by 23.6%, and decreasing the real feed pressure by 9.92%. Therefore, this effect increased the production of water in the system and extended the life of the membrane.The application of the zeta rod before the reverse osmosis membrane will affect the colloidal particles by adding them some efforts, so this keep them suspended and prevent the formation of sediments on the membrane