Why Does My Water Smell? 20 Potential Causes of Stinky Odors

If your tap water smells strange, it can be unsettling. Water may smell like rotten eggs, chlorine, metal, sewage, fish, gasoline, or musty earth. Some odors are harmless and temporary, while others can point to plumbing problems or contamination that should be addressed quickly.

Common Causes of Smelly Water

One of the most common odors is a rotten egg smell, often caused by hydrogen sulfide gas or sulfur bacteria. This may come from groundwater, a water heater, or plumbing bacteria. A strong chlorine smell may be related to municipal water treatment. A metallic smell can come from iron, manganese, copper, or old pipes.

Musty or earthy smells may come from algae, organic matter, bacteria, or stagnant water. Sewage odors can point to drain problems, venting issues, or bacteria in a sink overflow rather than the water supply itself.

20 Possible Sources

Potential causes include sulfur bacteria, hydrogen sulfide, iron, manganese, chlorine, chloramine, old pipes, corroded plumbing, water heater bacteria, stagnant water, algae, organic matter, well contamination, drain bacteria, sewer gas, faulty plumbing vents, dirty faucet aerators, contaminated filters, nearby industrial runoff, or fuel-related contamination.

Hot Water vs. Cold Water

Pay attention to whether the smell appears in hot water only, cold water only, or both. If only hot water smells bad, your water heater may be the source. If both hot and cold water smell, the problem may be the water supply or whole-home plumbing.

Check One Faucet or the Whole House

If only one sink smells, clean the aerator, drain, and overflow opening. If every faucet smells, consider testing your water. Private well owners should be especially proactive because wells are not monitored by a public utility.

When to Test Your Water

Test immediately if water smells like gasoline, chemicals, sewage, or if the odor appears suddenly and strongly. Also test if you have a private well, nearby construction, flooding, or health symptoms.

Final Thoughts

Smelly water can come from many sources, from harmless minerals to serious contamination. Identify whether the odor is hot or cold, one faucet or all faucets, then test or call a professional if needed. Clean, odor-free water starts with finding the true cause.