The rotten egg smell, and the free test that says where it starts
Hydrogen sulfide. It is common in Floridan aquifer water and it is not a sign that anything has broken. Before spending a dollar, run one tap and then another, because that comparison decides whether this is a cheap fix in the garage or treatment on the main line.
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Do this first. Two minutes, and it costs nothing.
Run the cold tap in a room you have not run hot water in recently, and smell it. Then run the hot tap and smell that. Then do the same in a second room, and outside at a hose bib if there is one that comes off the line before any treatment equipment.
- Hot water onlyThe magnesium anode rod in the water heater reacting with sulfate in the water. A plumber, an afternoon and one part. Nothing to do with the well, and no treatment system needed.
- Hot and cold, everywhereHydrogen sulfide in the water arriving at the house. This is the case that needs treatment on the main line, and the level decides which kind.
- One tap onlyBacteria in that fixture or its drain rather than in the water. Clean the aerator and the drain, then smell a glass of the same water in another room.
- Only after the house has stood emptyStagnation in the pipework or a little-used branch. Flush it through thoroughly before concluding anything.
Where it comes from here
Hydrogen sulfide is produced when sulfate-reducing bacteria in the aquifer or the well casing metabolise the naturally occurring sulfate minerals in the Floridan carbonate rock. That is a local explanation rather than a general one, and it is why this is far more common in central Florida than in the states whose extension pages dominate the search results.
What actually removes it
In rough order of how much sulfide each will handle, and therefore of cost. The right one is chosen from a test result, not from a description over the phone.
- Replacing the water heater anode rodOnly relevant to the hot-only case, and the cheapest outcome available. An aluminium or zinc rod in place of the magnesium one usually settles it.
- AerationExposing the water to air so the gas leaves solution, then venting it. Effective at low to moderate levels, no chemicals, and the maintenance is mechanical rather than consumable.
- An oxidising filterA media bed that converts the sulfide so it can be filtered out. Handles moderate levels and often deals with iron in the same unit, which is why it is common here.
- Chlorination followed by filtrationThe heavy end, for high sulfide and worth it when iron bacteria is in the picture too. More equipment, and it needs attention rather than being fitted and forgotten.
The questions people actually ask
Is it dangerous to drink water that smells like rotten eggs?
The smell itself is not the danger people assume. Hydrogen sulfide is detectable by nose at concentrations far below any level of health concern in drinking water, which is why it is treated as a nuisance rather than a health contaminant. The caveat worth taking seriously is that a new smell can mean something has changed at the well, and the things that genuinely matter for health, bacteria and nitrate, have no smell at all.
Why does only my hot water smell like sulfur?
The sacrificial anode rod in the water heater. It is normally magnesium, and it reacts with sulfate in the water to produce hydrogen sulfide inside the tank. The well is not the source. The usual fix is swapping the rod for an aluminium or zinc one, which is one part and an afternoon, and a plumbing job rather than a well job.
Will a water softener get rid of the rotten egg smell?
No. A softener is an ion exchange machine for calcium and magnesium and it does not remove dissolved hydrogen sulfide. If somebody has sold you one for the smell, that is what to raise with them. What does work is aeration, an oxidising filter, or chlorination and filtration, chosen according to how much sulfide the test shows.
The smell came on suddenly. Should I worry?
A sudden change is worth a test, where a long-standing smell mostly is not. Not because sulfide has become dangerous, but because something at the well has changed and the tests that matter for health would not announce themselves. Test for bacteria and nitrate alongside the sulfide, and mention the timing when you send the sample.
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About this guide
Ocala Well Water publishes an independent guide to private well water for homeowners in Marion County, Florida. It does not drill, repair, test or install anything, and it sells no equipment.
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