Why Does My Water Smell Like Rotten Eggs?

Coastal Rooter helps San Diego homeowners get rid of foul-smelling tap water caused by plumbing issues. If your water smells like rotten eggs, the source may be deeper than you think.

If you’ve ever turned on the tap and noticed a sulfur-like odor—similar to rotten eggs—you’re not alone. It’s a common problem in households across San Diego County, and while the smell is unpleasant, it can also be a sign that something’s wrong with your plumbing or water heater.

Here’s what causes water smells like rotten eggs, and how to get rid of it for good.

What causes water to smell like rotten eggs?

The most common reason water smells like rotten eggs is hydrogen sulfide gas. This gas forms when bacteria break down organic material in water that lacks oxygen. Even small amounts can cause a strong odor.

Common causes include:

• Sulfur-reducing bacteria in your pipes
• Reaction between magnesium anode rod and water in your heater
• Contaminated well water (less common in city systems)
• Stagnant water in unused plumbing lines

In San Diego, the smell often comes from water heaters or old plumbing that hasn’t been flushed or serviced in years.

How to tell if the smell is in hot or cold water

You can narrow down the source of the odor by checking where it happens:

• Only hot water smells? The water heater is the likely source.
• Both hot and cold water smell? The issue may be in the main water supply or pipes.
• One faucet only? It’s likely localized to that fixture or branch line.

This simple test helps plumbers figure out whether to inspect the heater, treat the water supply, or flush the plumbing system.

Problems with water heaters

Water heaters are a common cause of that rotten egg smell—especially older models with magnesium anode rods. These rods protect the tank from corrosion but can react with naturally occurring sulfates in the water, producing hydrogen sulfide gas.

Fixes include:

• Flushing the tank to remove bacteria and sediment
• Replacing the anode rod with an aluminum-zinc alloy version
• Sanitizing the system with hydrogen peroxide

Learn more about our water heater services if your hot water is the culprit.

Plumbing issues and stagnant pipes

If the smell comes from both hot and cold water or specific faucets, bacteria may be growing in your pipes. This often happens in unused fixtures, guest bathrooms, or outdoor plumbing that sits idle for weeks or months.

Running the water for a few minutes can help, but if the smell returns quickly, a deeper flush or pipe disinfection may be needed. Schedule a plumbing inspection to find the source.

In some cases, biofilm buildup inside pipes may require professional cleaning or replacement.

Is the water safe to drink?

In most cases, water that smells like sulfur is safe—but it’s not pleasant to use. If the smell is from your heater or internal pipes, it won’t harm you. However, if it comes from the main supply or a well, testing may be necessary.

Excess hydrogen sulfide gas can corrode pipes and damage metal parts, which leads to other plumbing issues over time. It can also alter the taste of food and make showers or dishwashing unpleasant.

Coastal Rooter can test and diagnose water quality concerns and advise on treatment options if needed.

What San Diego homeowners should know

Most city homes in San Diego receive treated municipal water, which is typically free from sulfur odors. But old plumbing, aging water heaters, or infrequently used pipes can still create the smell indoors.

Coastal Rooter technicians are familiar with local plumbing conditions and water chemistry. They help homeowners:

• Identify the exact source of the odor
• Flush or sanitize affected systems
• Prevent the smell from returning with simple maintenance

“We couldn’t figure out why our water smelled like rotten eggs. Coastal Rooter found the issue in our old water heater and fixed it the same day.” — San Diego homeowner

Long-term solutions and prevention

To avoid recurring odor issues:

• Flush your water heater annually
• Run unused faucets weekly to keep water fresh
• Replace magnesium anode rods with zinc-aluminum types
• Schedule routine plumbing checkups to catch buildup early

For homes with persistent odor despite flushing and repairs, a whole-house water treatment system may be recommended. Coastal Rooter can walk you through those options.

Learn more from the EPA’s drinking water guide if you have concerns about water safety.

When your water smells like rotten eggs

If your water smells like rotten eggs, call 619-383-2210 to book an inspection. Coastal Rooter finds the source and clears up the smell fast, so your water runs clean again.