You turn on the shower, and it smells like sewer gas. That is not a pleasant smell.
If your shower drain smells like sewage, you might be dealing with a simple clog, but in Phoenix-area homes, heat, hard water, and slab construction mean the real cause isn’t always obvious. Here’s what could be happening and how to know when it’s time to call a professional.
Why Does My Shower Drain Smell Like Sewage?
There are several possible causes. It might be buildup in the pipes, or it might be a more serious plumbing issue beneath your foundation.
Biofilm and Organic Buildup
In many cases, the smell is not raw sewage at all. It’s bacteria.
Bad smells in drains are often caused by microbial biofilms, including Pseudomonas and Sphingomonas, that thrive on hair and soap scum. These biofilms are caused by bacteria and can produce volatile organic compounds (VOCs) even if the drain isn’t clogged. In Phoenix homes, hard water and mineral sediment create breeding grounds for this type of buildup inside pipes. Combine that with hair, soap residue, and warm shower temperatures, and you have the perfect environment for odor-producing bacteria.
It sounds horrible, but it’s not usually a big problem. Biofilm buildup is usually the cause if you get a strong smell when you turn on the shower, and then the odor gets better after a few minutes.
Dry or Damaged P-Trap
Just like your sink, showers have a P-trap, that curved pipe underneath the drain that’s designed to hold water and block sewer gas from entering your home. Extreme summer temperatures and low humidity can evaporate water in traps fast, especially in bathrooms that aren’t used frequently.
During high heat, the water seal can dry out in as little as a week or two. And when the water barrier disappears, sewer gas rises directly through the drain.
Partial Drain Blockage
A slow-moving shower drain filled with hair and soap scum can also trap debris and create odor pockets. The water may still drain, but slowly.
Venting Problems
Your plumbing system relies on roof vents to release sewer gases outside. If your vent stack is damaged or blocked, gas can back up into your home. If the smell changes with the weather or appears after storms, venting may be involved.
Steps to Fix Sewage Smells from Shower Drain
You can often fix a shower drain that smells like sewage by trying a few simple steps:
- Run the shower for several minutes to refill the P-trap.
- Remove hair and debris from the drain.
- Use a drain cleaner to reduce biofilm buildup.
- Flush other nearby fixtures to ensure traps are filled.
If the odor disappears and doesn’t return, you’ve found the source and fixed it.
When a Shower Drain Smell Is More Than a Clog
However, if the smell doesn’t go away, there can be more serious issues to worry about. For example, if the smell doesn’t go away even after you’ve refilled the traps and cleaned the drain, you might have a sewer line problem. A slow-draining tub or shower that doesn’t respond to drain cleaner, or smells bad and makes gurgling sounds, might be a sign of a sewer line problem under the slab.
Also, if you see more than one drain in your home backing up at the same time, it’s likely not a clog but an issue with your main sewer line.
Does the sewage smell from your shower drain get stronger at certain times of the day? You might have an issue with your venting.
When Should I Call a Plumber for Sewage Smells from Shower Drain
Call the team at George Brazil Plumbing & Electrical if:
- Odors keep returning every few weeks.
- The smell spreads beyond the bathroom.
- You hear gurgling in nearby fixtures.
- You suspect the problem may be under the slab.
- The clog doesn’t clear or keeps returning.
If any of these conditions are occurring, ignoring it won’t make it go away. It’s time to call in the pros at George Brazil. We’ve been serving the Phoenix metro for more than 35 years and have 2,800+ five-star reviews from our loyal customers. We offer same-day service in most cases, and our technicians come with fully stocked trucks to handle most repairs on the spot.
Does your shower drain smell like sewage? Call George Brazil Plumbing & Electrical and schedule a professional inspection.