This is pretty clearly a grain silo and not a storage tank. If there's a conflict in tagging, the accurate tags should be kept and the conflicting tags removed or updated. Almost all silos near me lack a building tag but I have put the building tag back as building=silo. As you point out, our tagging scheme has lots of other sub-tags off "building:".

As a reminder using Google for mapping is not allowed. Bing StreetSide or Mapillary are similar services that have licenseing allowable for use in OSM mapping.