Interesting, are people expecting these man_made=water_tower areas to correspond to the footprint at the base or the maximum extent? The documentation doesn’t specify. Most water towers where I’m from are shaped like barrels or balls supported by pipestems, so there can be quite a difference:
Or is it like buildings, which should technically exclude any overhangs, but in practice often include overhangs because of limited information or attention? Personally, I normally don’t bother mapping water towers as areas, but I can understand the motivation since they cover more area than many buildings and other features that we usually map as areas.
Ironically, some of the lowest-quality imagery we have access to makes it much easier to map the footprint, if desired, due to obliqueness. Building imports can also introduce footprint-based areas. For example, this water tower’s footprint came from a building import apparently sourced from a LiDAR scan, but it would’ve been just as easy to map it by hand.
Fortunately, as with masts mapped as areas, renderers seem to be coping just fine with areas. Instead of preferring a node representation over an area representation or vice versa, we should just discourage guesswork: if you can’t visually determine the footprint, not even via a shadow, then either leave it as a node or map the maximum extent. Someone can come along later to transform it into a 3D building relation with building=roofs for the overhangs. 