Smell Gas but the Gas Company Found Nothing? Here’s What’s Happening

You called Peoples Gas because you smelled gas. A technician came, walked the house with an instrument, found nothing, and left. And you still smell it. Now you’re second-guessing your own nose while a small worry quietly grows. Here’s the thing every Chicago gas fitter knows and most homeowners don’t: a clean utility check does not mean there’s no leak. It means there’s no leak where and when they looked, on their side of the responsibility line. Those are very different statements — and the gap between them is exactly where the leaks I get called about live.

Why the Gas Company Can Find “Nothing” When Something Is There

Peoples Gas responds to gas-odor calls fast and for free, and that response is genuinely valuable — but it’s calibrated for one job: making sure there’s no immediate, dangerous accumulation and that their equipment up to the meter is sound. It is a triage sweep, not a forensic survey. A few realities of that visit explain the clean-but-still-smelling gap. Their priority is life-safety and their own infrastructure, so a small private-side weep that isn’t building to a dangerous level can read as “no hazard found” — which is true, and still not the same as “no leak.” Their instruments sample the air where they walk, at the moment they walk it; a leak venting into a wall cavity, under a slab, or into a spot air isn’t moving through can simply not reach the sensor. And crucially, everything past the meter is your responsibility, not theirs — they’re not there to trace your branch lines joint by joint. None of this is negligence. It’s the scope of the service. The mistake is reading “we didn’t find a hazard” as “there’s nothing to find.”

The Four Leaks That Hide From a Quick Check

• ✓ The slow weep. A joint losing gas so gradually it never builds to a level that trips a fast sweep — but enough that you smell it in a closed room overnight. These are the bread and butter of private-side detection.
• ✓ The intermittent leak. A fitting that leaks only under certain conditions — when an appliance cycles, when the pipe warms and expands, when pressure shifts. If it wasn’t venting during the utility’s visit, it wasn’t there to find.
• ✓ The hidden leak. Gas escaping into a wall cavity, under a concrete slab, or behind cabinetry, where it accumulates and seeps out slowly somewhere else. The smell reaches you; the gas never reaches their sensor where they stood.
• ✓ The below-threshold private-side leak. Real, ongoing, and on your piping — but small enough that a safety sweep focused on hazards logs it as no immediate danger and moves on.

Trust Your Nose: Odorant and Why You Smell It for a Reason

Natural gas is odorless; the rotten-egg smell is mercaptan, an odorant added specifically so humans can detect tiny concentrations. Your nose is, in effect, a calibrated leak detector the gas company itself is relying on — that’s the whole point of adding the smell. So when you keep smelling gas after a clean check, the rational move isn’t to doubt yourself; it’s to bring in an instrument that looks harder than a safety sweep does. One caveat worth naming: if the smell is strong, spreading, or paired with hissing or physical symptoms, that’s not a “still smells” situation — that’s an active emergency, and you leave and call 911 and Peoples Gas again from outside immediately. The trust-your-nose-and-investigate advice is for the persistent faint odor that survives a clean visit, not for a smell that’s getting worse.

What a Private-Side Detection Actually Does Differently

When I come out for a “they found nothing but I still smell it” call, I’m doing a fundamentally different job than the utility did. I’m not triaging for immediate hazard — I’m hunting for your leak on your piping, systematically. That means instrument-tracing the branch lines joint by joint, checking the spots a walking sweep skips, and when the smell is intermittent or hidden, using the definitive tool: a pressure test. A pressure test doesn’t rely on catching gas in the air at the right moment — it isolates a line, pressurizes it, and watches whether it holds. A line that’s leaking anywhere along its length fails the test, whether or not it happened to be venting when anyone was standing there. That’s how the intermittent and hidden leaks get caught: not by smelling for them, but by proving the pipe can or can’t hold. Detection runs $75–$400 by scope; a pressure test is $75–$150 per line with a signed affidavit. For the deeper how-and-why of finding leaks, our detection page covers the method.

Still Smell Gas After a Clean Check? Answered Straight