I while back I had a problem with my mill, had to shop vac a pound or 2 of grain. A few weeks later got a real bad fruit fly problem. Bleaching, bombing, sweet traps, fly strips...nothing worked. So then I was moving my vac and bumped off the lid and was met by a biblical horde of flies. And what was growing in the bottom was the spawn of Satan. My wife had used it to vac up a water spill. Unfortunately, there wasn't enough liquid to fill a hydro tube. But the iodine test was negative.