Quick take
Test manganese, iron, pH and sulfur before choosing equipment. Manganese treatment is highly chemistry-dependent.
Manganese is a common cause
Manganese can produce dark brown or black staining and may occur alongside iron. It can also foul softener resin and filter media if untreated.
Sediment can mimic manganese
Dark particulate from the well, plumbing or pressure tank can look similar to mineral staining. Catching particles in a clear container can help distinguish settled sediment from dissolved-water staining.
Treatment depends on pH and concentration
Oxidation media, air injection and other well-water systems can treat manganese, but performance changes with pH, competing iron and flow rate.
Best first purchase is often a test
A proper water test is cheaper than installing the wrong whole-house system. Tap Score and local accredited labs fit this intent well.