That rotten-egg odor is almost always caused by hydrogen sulfide gas (H₂S). Think of it as the flatulence of the underground mineral world. This gas dissolves into your well water from decaying organic matter or certain bacteria that live in your aquifer, munching on sulfur and iron.
Here’s a surprise: that smell isn’t necessarily dangerous at low levels, but it is a massive red flag. If you smell it strongly, you might also have iron or manganese bacteria partying in your pipes, leaving a slimy biofilm that’s both gross and cloggy. Your water might also taste metallic and leave rusty stains on your sink.
One crazy fact: if you have very high levels of hydrogen sulfide, it can actually kill your water heater’s anode rod faster than you can say “plumber’s bill.” That’s the metal rod that prevents your tank from rusting into a colander. So, yes, the smell is costing you money.
