Rotten Egg Smell in Well Water: Causes and Fixes

If you live on a private well anywhere from Ocala down through Lake County, there is a good chance you have smelled it: you turn on the shower and the bathroom fills with the scent of rotten eggs. The culprit is almost always hydrogen sulfide gas. Florida's aquifer and the low-oxygen conditions deep underground make sulfur water common here. The good news is that it is very treatable once you know where the smell starts.

Start with the hot-versus-cold test

Fill one glass with cold water and another with hot, step away from the sink, and smell each one. This two-minute test narrows the cause more than anything else you can do at home.

• •Only the hot water smells: the water heater is producing the gas. This is a tank problem, not a well problem.
• •Both hot and cold smell: hydrogen sulfide is in the groundwater itself, and treatment belongs at the point where water enters the house.
• •Only one faucet smells: the odor may come from bacteria in that sink's drain, not the water. Smell the water in a glass away from the basin.
• •The smell is strongest after the water sits overnight: that can point to sulfur bacteria in the well or plumbing.

Fixing a smelly water heater

Most tank heaters come with a magnesium anode rod, which protects the steel tank by corroding in its place. In well water containing sulfate and certain bacteria, that reaction produces hydrogen sulfide. Swapping in an aluminum-zinc anode or a powered anode usually solves it, often combined with flushing the tank. Do not simply remove the anode. Without it, the tank will corrode quickly and fail early.

Treating sulfur in the well water

The right system depends on how strong the smell is and what else is in your water. Iron and sulfur often show up together in Central Florida wells, so a water test that includes hydrogen sulfide, iron, manganese, pH, and hardness keeps you from buying the wrong equipment.

• •Air injection oxidizing filters: a pocket of air in the tank converts dissolved sulfur into particles that the filter bed traps and backwashes away. Good for light to moderate levels without chemicals.
• •Chlorine or hydrogen peroxide injection: a small pump feeds an oxidizer into the line, followed by a contact tank and carbon filter. Best for strong odors or when iron bacteria are present.
• •Catalytic carbon: works well for lower levels and as a polishing stage after oxidation.
• •Shock chlorination: disinfects the well and plumbing if sulfur bacteria are the cause. It often brings temporary relief, but the smell returns if the groundwater itself is the source.

Why it can appear suddenly

Homeowners in Sorrento and Umatilla sometimes tell us the water was fine for years and then started smelling overnight. Common triggers include a new water heater with a fresh magnesium anode, a drop in water use that lets water sit longer, seasonal changes in the water table, or a well that has developed a bacteria colony. A fresh test usually explains what changed.

• Water filtration systems
• Well pump service
• How to test well water in Florida