[Tagging] man_made=storage_tank for open containers?

[Markus]

On Sat, 9 Feb 2019 at 23:44, Warin <61sundowner at gmail.com> wrote:
>
> Perhaps use the tag covered=no to signify an uncovered storage tank?

According to the wiki, covered=no would signify that the storage tank
isn't covered by something else, not that it isn't closed. Therefore
my suggestion with open_top=yes (or maybe just open=yes).