Houston Duct The Reservoirs, the Flood, and What Actually Got Wet
When the Army Corps opened the Addicks and Barker reservoirs during Hurricane Harvey, water didn't just rise along the bayous — it backed up into neighborhoods that had never flooded before, because the pools themselves became the flood. Roughly 14,000 homes sit inside those two reservoir footprints, and about 5,138 of them took on water in 2017. That's a specific number, not a rounded-up guess, and it matters because the flood pattern inside the pools was unusual: water came up from the ground floor, not down from a roof leak or a burst line. For most of these houses, that meant the attic — where the ductwork lives — stayed completely dry.
That's the part people get backwards when they call asking about duct cleaning after Harvey. The ducts weren't underwater. The living space was. But a flooded first floor still means a gutted, dried-out, and rebuilt house, and a rebuild means months of drywall cutting, sanding, and foot traffic with the HVAC system sometimes running the whole time. The ducts came through the flood dry and came out of the rebuild dirty.
Why the Dust Problem Outlasted the Water Problem
Drywall dust is fine enough to pass straight through a one-inch filter, and a system that ran during the demo-and-rebuild phase pulled that dust through the returns and dropped it wherever the airflow slowed down — the boots, any low sag in a flex run, the floor of the plenum. Multiply that by a rebuild that often took months, and you get a system that's never seen a drop of water but is loaded with the same fine gray silt you'd find in a kitchen remodel that didn't cover its registers. If your Katy or Cinco Ranch home went through a post-Harvey rebuild, that's almost certainly what's sitting in the ducts now, not storm water residue. Our duct cleaning after a remodel or a new build page covers the same mechanism in a kitchen-remodel context, and it applies just as directly to a whole-house flood rebuild.
Telling Original Flex From Replaced Flex
A lot of these houses also had sections of attic ductwork replaced during the rebuild, even though the attic itself stayed dry — sometimes because a contractor was already up there running electrical or insulation and it was easier to swap a run than inspect it, sometimes because a homeowner asked for it as part of the larger job. Years later, most owners have no paperwork telling them which runs are original and which are new. You can tell by looking:
- Check the jacket surface. Original flex duct that's spent years in a Gulf Coast attic, where summer temperatures routinely top 120°F, typically looks dull and feels stiff when you press on it.
- Flex it gently by hand. Replaced sections are usually still shiny and noticeably pliable — the outer vapor jacket hasn't had years of heat cycling to dry it out.
- Compare runs side by side. In a house with mixed original and replaced duct, the contrast is often obvious once you're looking for it — one run bends easily, the next is almost rigid.
- Note the transitions. Replaced sections usually show cleaner, newer collar connections and straps than the original runs around them.
None of this is a pass/fail test on its own, but it tells a technician where to look closer, and it's exactly the kind of detail our flex duct assessment covers before anyone recommends cleaning versus replacing a run.
The Rule for Duct That Was Actually Underwater
Some homes inside the pools did take water high enough to reach a low soffit return or a duct run near a garage ceiling. The rule here doesn't bend: any duct that was genuinely submerged gets replaced, not cleaned. Insulated flex duct is porous. Once contaminated floodwater has soaked into the liner, no amount of brushing, vacuuming, or sanitizing reaches what's inside the insulation, and the material can't be verified clean afterward. A licensed contractor cuts it out and replaces it — the same standard applied to any duct chewed through by pests or compromised by long-term moisture. Anything above the waterline, and everything in a dry attic that just needs the drywall dust pulled out, is a legitimate cleaning job.
If you're in the Katy or Cinco Ranch area and you're not sure which category your system falls into, that's a question worth answering before any cleaning quote — our Katy and Cinco Ranch page has more on how we handle that assessment locally.
The short version for any reservoir-area homeowner: dry attic plus rebuild dust is a cleaning job, and any duct that was actually underwater is a replacement job, not a cleaning one.