UMass researcher outlines treatment options and limits for manganese in drinking water

John Tobiasen, professional emeritus and part-time research professor in the Department of Civil and Environmental Engineering at UMass Amherst, described how manganese occurs in source waters and reviewed practical treatment approaches during an RCAP Solutions webinar on Sept. 16.

Tobiasen said manganese commonly appears in both groundwater and seasonally in surface waters and that its form — dissolved versus particulate — matters for treatment. He said aesthetic problems such as staining and turbidity often drive treatment needs, but manganese was put on the U.S. EPA contaminant candidate list and monitored under UCMR4 because of potential health concerns. "Manganese should be at 10 to 20 micrograms per liter," Tobiasen said, stating that levels below about 0.02 milligrams per liter help avoid chronic problems in distribution systems.

Why it matters: manganese interacts with other treatment concerns (iron, natural organic matter, PFAS) and can dominate treatment chemistry and costs. Tobiasen emphasized that treatment plans must account for chemical speciation, competing oxygen demand, and reaction kinetics rather than relying on simplified rules of thumb.

Key technical points Tobiasen presented: - Forms and occurrence: manganese occurs dissolved (Mn2+) under reducing…