What Causes That Rotten Egg Smell in Your Water?

Noticing a sulfur-like odor when you turn on the tap? That unpleasant rotten egg smell is often caused by hydrogen sulfide gas in your water. While it’s not typically dangerous at low levels, it can affect your water’s taste, stain plumbing fixtures, and contribute to bacteria buildup. At Aquatek Water Conditioning, we know how this smell can impact your water supply and we’ve helped hundreds of homeowners across northwest Ohio and southeast Michigan eliminate that smell for good.

So what causes it—and more importantly, how do you stop it? Let’s walk through the science behind the smell, how to identify the source, and the most effective solutions available to take care of the issue.

The Science Behind the Smell: Hydrogen Sulfide in Water

Hydrogen sulfide is a naturally occurring gas that can enter your water from underground decay, sulfate-reducing bacteria, or even chemical reactions in your plumbing or water heater. When it dissolves in water, it produces the distinct smell of rotten eggs—especially common in well water systems.

Is Hydrogen Sulfide Harmful?

In small amounts, it’s considered a nuisance rather than a health risk. But left untreated, hydrogen sulfide can corrode pipes, damage appliances, and create an environment where bacteria thrive. According to the EPA, nuisance contaminants like this should still be addressed for home safety and water quality.

How to Tell If It’s in Your Water

If the odor only occurs when using hot water, your water heater may be to blame. Magnesium anode rods inside water heaters can react with sulfates, creating hydrogen sulfide gas. If you notice the smell in both hot and cold water, the issue likely originates in your well or plumbing system.

Localized odors from specific faucets could mean bacteria in your pipes. The CDC notes that sulfur-reducing bacteria are often to blame in these cases, especially in anaerobic (oxygen-free) environments.

Why Well Water Often Has That Sulfur Smell

Well water users are more likely to notice the rotten egg odor. That’s because groundwater can pick up sulfur compounds from surrounding rocks and soil. The USGS explains that deep wells with low oxygen levels are prime environments for hydrogen sulfide to develop—especially where sulfur-reducing bacteria are present.

Steps to Identify the Source

• Test your water: Get a lab-based water test to measure hydrogen sulfide and identify other potential contaminants.
• Check for bacteria: Sulfate-reducing bacteria are often the cause. Their interaction with organic matter can produce noticeable odors.
• Inspect your well: Look for cracks or leaks that could be allowing organic materials to contaminate your water.

Effective Treatment Options for Well Water

• Oxidation Filtration: Air injection or chemical oxidizers like chlorine convert hydrogen sulfide to solids, which are then filtered out. These are highly effective systems offered by Aquatek.
• Activated Carbon Filters: Ideal for low sulfur levels, these filters improve taste and odor but need regular replacement.
• Shock Chlorination: A one-time treatment to eliminate bacterial contamination—especially helpful after servicing your well.
• Chemical Feed Systems: Continuous injection of chlorine, hydrogen peroxide, or ozone to treat high levels of hydrogen sulfide.

Could Your Water Heater Be the Culprit?

If the smell only occurs when using hot water, your water heater is likely the issue.

• Magnesium anode rods often react with sulfates, producing hydrogen sulfide gas.
• Cool water temperatures in the tank can promote bacterial growth.

Water Heater Fixes

• Flush the tank to remove buildup.
• Replace the anode rod with aluminum or zinc alternatives.
• Temporarily raise the water heater temperature to kill bacteria.

Best Long-Term Fixes for Sulfur Smell

The right solution depends on what’s causing the smell—whether it’s bacteria, hydrogen sulfide gas, or your water heater.

Below are some common solutions that we commonly recommend based on water type, however, each situation is unique and should be evaluated by a professional.

• Well water: Install an oxidation filter or chemical injection system for full treatment.
• City water: Carbon filters or reverse osmosis may be enough to improve odor and taste.
• Hot water only: Anode rod replacement or whole-home filtration may be needed.

Frequently Asked Questions

Is smelly water safe to drink?
It depends on the cause. Hydrogen sulfide isn’t usually harmful at low levels, but bacteria-related contamination can be. A professional test is the best way to know.
Why does my hot water smell like sulfur?
Your water heater may contain a magnesium anode rod that reacts with sulfates in the water, releasing hydrogen sulfide gas.
How can I get rid of the rotten egg smell?
Treatment depends on the source—options include oxidation filters, chemical feed systems, or replacing water heater components.

Take the First Step Toward Cleaner, Odor-Free Water

Don’t let smelly water affect your home comfort. Schedule a water test with Aquatek Water Conditioning today to pinpoint the cause and get the information you need to make the right choice for your home.

Whether your water comes from a well or a city supply, we’re here to help you enjoy cleaner, fresher water every time you turn on the tap. We’ve been serving our neighbors in Ohio and southeast Michigan since 1952. Aquatek is your trusted partner in long-lasting water solutions.