Iron bacteria are alive, which is why they come back.
What it is
Iron bacteria are naturally occurring organisms that take their energy from dissolved iron and leave a gelatinous orange or brown mass behind. They are not regarded as a health organism the way coliform is, but they colonize the well, the pump, the pressure tank, and the pipework, which is what makes them stubborn. A lab confirms them by culture rather than by a number.
What it usually does
They usually leave orange jelly on toilet tank walls and flappers, an oily-looking rainbow sheen on standing water, and a swampy or fuel-like smell that is actually the colony rather than any fuel. Over time they clog screens, well points, and pressure switches, and they will foul filter media and softener resin.
What it does not prove
Finding iron bacteria does not mean coliform or E. coli is present, and the absence of them does not mean a well is clear of anything else. The rainbow sheen in particular is often mistaken for fuel contamination. A sheen that shatters into pieces when poked is usually bacterial, while an oil film usually swirls back together.
When to test
Usually worth confirming by lab before any shock chlorination, and worth testing coliform at the same time since the sample is already being drawn. Treatment is usually a disinfection plan rather than a filter, so it is planned off the panel.
See what this usually means for your water.
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