So, who’s the culprit behind this stinky mystery? Most of the time, it’s not your pipes, and it’s not the water company. It’s a bunch of microscopic party crashers called sulfate-reducing bacteria. These tiny guys live in the water heater, in the well, or even in the drain. They don’t need oxygen to survive; instead, they munch on sulfates naturally found in water.
When these bacteria eat, they burp. And what’s their burp? Hydrogen sulfide gas—the exact same chemical that makes rotten eggs smell so awful. Pretty wild that a teeny-tiny organism can create such a huge, memorable stink, isn’t it?
Your Water Heater: A Bacteria Spa
Here’s where it gets really cool: your water heater is basically a cozy, dark, and slightly warm vacation home for these bacteria. If you set your heater too low—say, under 120°F (about 49°C)—the water isn’t hot enough to kill them. They just settle in, throw a microscopic feast, and the result is that eggy aroma every time you run the hot water.
It’s like leaving a gym bag in a warm car for a week. The combination of warmth and lack of oxygen is basically their paradise. Ever notice the smell is only in the hot water, not the cold? Bingo. That’s your hot water heater talking.
