Within recent years more and more effort has been devoted to reducing the destructive action of some waters on the pipes which carry them to the consumer. These efforts are based upon fairly simple chemical concepts and in many instances are not costly. The Bureau of Sanitary Engineering of the State Department of Health of Maryland has been called upon in the last few years to recommend procedures for the elimination of the corrosiveness of several public water supplies. Data have been accumulated as to the causes of such corrosion and as to processes which materially reduce or eliminate these disabilities. The practical results obtained in full scale operation in some of these cases are here reported. Measures for the reduction or elimination of corrosion of the distribution system have been introduced for the treatment of the water supplies of a number of small communities in Maryland, covering a total population of between 25,000 and 30,000. They are referred to here in individual examples with sufficient analytical data to make clear the principles of treatment.