Key Takeaways:

• The Test: Smell your cold water. Smell your hot water. If ONLY the hot water smells like eggs, your well is fine.
• The Culprit: Your water heater's magnesium "anode rod" is reacting with natural sulfates in the water, creating hydrogen sulfide gas.
• The Fix: Replacing the standard magnesium rod with an aluminum/zinc alloy rod usually stops the smell immediately.
• Don't Remove It: Never simply remove the rod without replacing it, or your water heater tank will rust and fail.

A "rotten egg" smell in your water is a classic sign of hydrogen sulfide gas. But if you only notice the odor when you turn on the hot taps, the good news is that the problem is almost certainly your water heater—not your entire water supply.

The Culprit: A Chemical Reaction in Your Water Heater

Most standard water heaters have a "sacrificial" anode rod, usually made of magnesium or aluminum. Its job is to corrode over time to protect the steel tank from rusting.

However, if your water has naturally occurring sulfates (which are harmless) and sulfate-reducing bacteria, a chemical reaction can occur with the magnesium anode rod. This reaction produces hydrogen sulfide gas, which gets trapped in the hot water tank and released when you open a faucet.

How to Diagnose the Problem

The test is simple:

1. Smell the cold water from a faucet.
2. Smell the hot water from the same faucet.
3. If the cold water is fine but the hot water smells, the issue is inside your water heater.

The Permanent Solution

While a whole-home sulfur filter is needed for wells with a persistent sulfur issue in both hot and cold water, this specific "hot water only" problem has a simpler fix:

1. Flush the Water Heater: This can help remove some of the bacteria.
2. Replace the Anode Rod: A plumber can replace the standard magnesium rod with a special aluminum/zinc alloy anode rod. This different metal composition does not react with the sulfates in the same way, stopping the production of hydrogen sulfide gas.

This is a common issue, especially for homes on private wells in North Texas. Addressing the anode rod can often solve the odor problem completely without the need for a larger filtration system.

---

Reviewed by Sai Akash Tumu, TCEQ Licensed Water Treatment Specialist (#WT0007448). Our approach is to educate first. For a personalized assessment, contact us for a free consultation.

---

Disclaimer: This guide is for informational purposes only. Water conditions vary, and we recommend a professional on-site water test for an accurate solution. This is not medical advice. Read full disclaimer >