Iron, Manganese and Sulfur Smell
Fixing orange stains, black specks and rotten-egg odor.
Iron and manganese
EPA's secondary (aesthetic) standards are 0.3 mg/L for iron and 0.05 mg/L for manganese; above those, expect orange and black staining. A softener can handle small amounts of dissolved iron, but higher levels need an oxidizing filter. HomeGuide prices the equipment at $400 to $1,200 (Birm), $600 to $1,800 (greensand), $800 to $2,500 (air injection) and $500 to $2,000 (chlorine or peroxide feed).
Hydrogen sulfide
The rotten-egg smell usually comes from sulfur bacteria or hydrogen sulfide gas. If it is only in hot water, the water heater anode rod is often the culprit. If it is in cold water too, air injection or peroxide treatment is common.
Iron bacteria
Slimy orange or brown residue in toilet tanks points to iron bacteria. Shock chlorinating the well and treating continuously may be needed.
Sources
Sources: EPA, Secondary Drinking Water Standards; HomeGuide, Well Water Filtration System Cost (Apr 24, 2026). Retrieved Oct 11–13, 2026.
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