It starts as a faint whiff. You check the trash can. You check the toilet. You check the p-traps under the sink. Everything looks clean, and the water is draining perfectly fine.
But the smell persists. A distinct, sulfur-like “rotten egg” odor that comes and goes, especially when the AC kicks on or the weather changes.
If you live in a San Antonio home built before 1985 (especially in neighborhoods like Castle Hills, Windcrest, or Alamo Heights), that smell isn’t just a nuisance. It is likely a sign that your cast iron sewer pipes are failing in a very specific, invisible way.
The Mystery: Why Smell But No Clog?
Most homeowners assume that if a pipe is broken, water will leak out.
But in older cast iron systems, we often see a phenomenon called “Crown Rot.”
Sewer gas contains hydrogen sulfide, which can turn into sulfuric acid inside your pipes. Because sewer lines are rarely 100% full of water, this gas floats to the top of the pipe. Over decades, that acidic gas eats away at the top (the crown) of the cast iron pipe, causing it to rust through and crumble.
The result: The bottom of the pipe is still intact, so water flows normally (no clogs!). But the top of the pipe is riddled with cracks and holes, allowing dangerous sewer gas to escape into your walls, under your slab, and into your home.
The Health Risk
Sewer gas isn’t just gross; it’s dangerous. It contains methane and bacteria that shouldn’t be breathing in. If you are smelling it, there is a breach in your sanitary system that needs to be closed.
How Do We Find a Leak We Can’t See?
Since the leak is often gas, not water, a standard camera inspection might miss hairline cracks at the top of the pipe.
At Drain Connection, we use Vapor/Smoke Testing.
We pump a safe, non-toxic smoke into your sewer system and pressurize it. Then, we walk through your home and yard. Wherever we see smoke escaping—whether it’s from a baseboard, a crack in the foundation, or a spot in the yard—we know exactly where the breach is.
It’s the fastest, most accurate way to “see” the smell.
The Solution: You Don’t Have to Dig
If we find “Crown Rot” in your cast iron pipes, the old-school solution was to jackhammer up the foundation and replace the pipe.
Today, we can save the pipe (and your floors) with Trenchless Pipe Lining. We insert a structural epoxy liner that inflates inside the old pipe, creating a brand-new, gas-tight pipe within the old shell. It seals off the cracks, stops the smell instantly, and lasts for 50+ years.
Stop the Smell Today
If you are tired of lighting candles to hide the scent of your plumbing, let us find the source.
Drain Connection specializes in diagnosing and repairing aging cast-iron systems in San Antonio.
- Suspect a leak? Learn more about our https://www.drainconnection.com/sewer-inspection/.
- Ready for answers? Call Us at (210) 529-8848 or visit our contact page.