Well made furniture can support a tank, but there's a caveat. You need to determine where the weight bearing members are and make sure that the tank contacts them completely. I used to keep 4 10 gals on a dresser that measured 19.5" from front to back. The tanks were arranged side by side with the end panels facing forward and stayed there with no problem for 3 yrs. And I still used the dresser for clothing. But if I tried to support a single 5 gal on the top panel I have no doubt it would have at least sagged if not failed completely.