We Get This Call Often. Water in the ducts is bad news We have a flood pumper and we can suck the water out of the ducts. Then we spray in sanitizer to kill mold, mildew, fungi, yeast and algae germs and bacteria. Regardless of what type of sub-slab ductwork is present, water is the main concern. If water finds its way into sub-slab ductwork, mold can follow. This leads to poor indoor air quality and health concerns. That stuff at the top of the duct in the picture below sure looks like mold, doesn’t it? Water in sub-slab ductwork The biggest concern with all sub-slab ductwork is the potential for water to enter the ducts, which is what today’s blog post is all about. Side note: sub-slab ductwork is ductwork installed below the concrete floor. If you’re buying a home with sub-slab ductwork, make sure that your home inspector checks the sub-slab ductwork for any signs of past water intrusion. Signs of water intrusion are a major concern because it’s usually not a simple repair....