There is no one answer for your question. There are many factors that can contribute to moisture on your basement floor. Water table levels, drainage, type of soil under the cement are just a few. Also humidity levels in the basement can sometime create moisture on a cool cement slab.

Hydrostatic testing can shed light on it for you.

You can try the following:

1.Clean and dry a section of your floor.

2. Take a piece of plastic wrap and duct tape it to the floor in your basement.

3. Over time, check to see if moisture is under the plastic wrap or on top of it.

Good Luck

Thanks. Now why didn't I think to do that! I am on my way to the basement to give this a try.