Iron & Manganese (Secondary Maximum Contaminant Levels = 0.3 & 0.05 mg/L respectively)
Iron and manganese occur naturally in New Hampshire’s geology. They dissolve into groundwater as acidic rainfall percolates through soil and rock. In higher concentrations, they can cause staining on laundry and water fixtures or occasionally will give an oily appearing, “crusty” sheen to the water’s surface. Iron or manganese can also give a metallic or vinyl type taste to the water, or may also support the growth of iron bacteria. While iron bacteria is not associated with adverse effects to human health, it can clog strainers, pumps and valves.
EPA, at present, has not yet set health standards for either iron or manganese in drinking water. However, the NH DES Health Risk Assessment Program has adopted an interim health based standard for manganese of 0.84 mg/L based upon studies manganese may have neurological and muscle function effects in humans.
For more information, please refer to the following NH DES fact sheets:
WD-WSEB-3-8 Removal of Iron and Manganese From Drinking Water – A Summary
ARD-EHP-15 Manganese Health Information Summary