This article is based on data accumulated by AWWA Task Group 2680 P‐Manganese Deposition in Pipelines. Manganese is a common ingredient of impounded water and of many well waters. In public supplies, it causes such difficulties as staining of clothes and plumbing fixtures, “black” water, incrustation of mains, and interferences with the colorimetric chlorine residual test. In industrial supplies, it causes severe economic losses through discoloration of products, specks in finished goods, and reduction of pipeline carrying capacities. Chemical reactions are generally presumed to account for the greater part of the manganese in groundwater; in stored water, manganese builds up by a combination of biologic and chemical processes working simultaneously. It is difficult to obtain clear‐cut statements about the economic significance of manganese in water supplies. In spite of this, requests increase yearly for information on how to remove manganese, how much the process will cost, and what method will best suit a specific water supply. This article discusses the reporting of manganese, manganese‐reporting organisms, manganese determination, filter media, manganese stabilization, and manganese removal by the zeolite process or by oxidation.