Why Does My Shower Drain Smell Like Rotten Eggs? The Science, Solutions & Savings

That foul rotten egg odor from your shower drain isn’t just unpleasant—it signals potential health risks and plumbing damage. Over 65% of homeowners experience this issue (EPA), often caused by hydrogen sulfide gas from bacteria. This guide breaks down the causes, data-backed fixes, and long-term prevention strategies.

The Science Behind the Stench

Rotten egg smells stem from hydrogen sulfide (H₂S) gas, produced when sulfate-reducing bacteria (SRBs) thrive in drains. Key triggers:

• Organic buildup: Hair, soap scum, skin cells.

• Low water use: Stagnant pipes in guest bathrooms.

• Water heater issues: Magnesium anodes corroding.

• Sewer line problems: Cracks or dry P-traps.

Diagnose the Source: Where’s the Smell Coming From?

Step-by-Step Solutions: Costs & Effectiveness

1. DIY Cleaning (Under $20)

For biofilm/slime buildup:

| **Method**            | **How-To**                          | **Cost** | **Effectiveness** | **Frequency**     |  
|-----------------------|-------------------------------------|----------|-------------------|-------------------|  
| **Baking Soda + Vinegar** | 1 cup baking soda + 1 cup vinegar | $3       | 70% (mild cases)  | Weekly            |  
| **Enzyme Drain Cleaner** | Pour 2 oz, wait 30 mins, flush   | $10      | 85%               | Monthly           |  
| **Boiling Water**       | 4–6 cups poured slowly            | $0       | 50%               | Bi-weekly         |  
| **Bleach Solution**     | 1:10 bleach/water, soak 15 mins  | $5       | 80% (caution*)    | Emergency only    |  

⚠️ Avoid bleach with septic systems—kills good bacteria.

2. Professional Repairs ($100–$1,000+)

Bacterial Hotspots: Where Biofilm Hides

| **Drain Component** | **Bacteria Concentration (CFU/cm²)** | **Risk Level** |  
|----------------------|--------------------------------------|----------------|  
| P-Trap               | 10,000–100,000                       |