A majority of reverse osmosis plants (RO) around the world are designedand operated with the continuous injection of acid to lower the pH of the feed water to reduce the scaling potential of the highly concentrated brine before discharge. As demand for RO plants increases, the associated consumption ofacid, typically 93% sulfuric acid, and worker and equipment exposure to this corrosive and potentially hazardous chemical have become very significant issues. A variety of antiscalants developed to simultaneously control all scales at commonly 1-5 ppm dosages have now been extensively demonstrated in the field. This paperpresents an implementation of acid elimination in a major municipal waterworks system. The paper reviews the chemistry behind acidification to prevent calcium carbonate scale. The mechanisms of calcium carbonate scaling and its avoidance by acidification or with antiscalants are discussed. The specific conditions at the Mount PleasantWaterworks RO plant in Mount Pleasant, South Carolina, are then addressed. Includes 10 references, tables.