Surface and ground waters rarely contain more than 1 mg/L of soluble or suspended manganese. Manganese can act as an oxidizing or a reducing agent depending on its valence state. Manganese is also used in the manufacture of batteries and as an alloying metal in the manufacture of steel and aluminum. Manganese concentrations in potable water should not exceed 0.05 mg/L. Concentrations greater than 0.1 mg/L will impart a foul taste to water and discolor laundry and porcelain surfaces. CHEMetrics' tests employ the periodate chemistry that measures soluble manganese compounds but does not differentiate the various valence states. Results are expressed as ppm (mg/L) Mn.