The Lionel spheroid works well too, it shows up in the catalogs in various decorations from time to time. This was the original without the LED on top, I've long since removed the lettering:
Or, if you can find one, Athearn once made an HO water tower that will also pass. I replaced the Lionel one with it because I wanted an older tower:
The beauty of water towers is they come in all sizes. I've seen some pretty small towers in some rural communities.
Rusty