Yes, you can use wet-dry vacuums on hardwood floors as long as they're sealed. Some wet-dry vacuums have more water output than others, but among the ones we tested, the water output is not too significant to cause concern. That said, you don't need to mop your hardwood floors more than once a week. Always check to see that the wheels don't cause any scratches on your hardwood floors. That did not occur with any of the we tested. However, we did find some wheels glided more smoothly on our hardwood floors than others, like the rubber wheels on the Tineco S7 Pro. Lastly, some cleaning solutions could damage your hardwood floors over time, so it's probably best to use the cleaning solution provided by the wet-dry vacuum only once a month.