Iron isn’t inherently evil; it’s the fourth most abundant element on Earth. But in your drinking water, too much of it can turn laundry dingy, clog pipes, and give your morning coffee a bizarre, metallic tang. Beyond the aesthetic horrors, excessive iron can harbor bacteria that feed on it, called iron-reducing bacteria, which create slimy biofilm. That’s the stuff you absolutely don’t want on your toothbrush.
The EPA sets a secondary maximum contaminant level of 0.3 mg/L for iron. Hit that mark, and you’re officially in “rust zone” territory. But here’s a cultural reality check: if you’ve ever complained about “hard water” at a dinner party, you’ve basically become your parents.
