f3922471_ater_Standards_and_Definitions__AGENT
[ACCEPTABLE or SAFE LIMITS] Less than 0.05 mg/L [SOURCES] Natural deposits [EFFECTS] Black or brown staining of fixtures Perhaps black-brown string or yarn-like substance in toilet tanks Can impart unpleasant taste, often bitter or metallic in taste Higher levels have been linked to impulse control & short fuse response in children [AGENT] 
Manganese
Haskell Water Treatment Drinking Water Standards and Definitions
AGENT