issue: this shower ain't public, and at least om offers no way to tell.

perhaps someone can signal this?

and i would like to know if osm uses a tag to point for public places where we can use water to clean ourselves!

some basins, lakes, waterfalls, beaches, etc, work for that. others do not. same for public swimming pools (almost none offer the option to just take a shower, but some do, and others are at least quite cheap and simple, close enough to "free"), and i even found a public free shower in an otherwise regular road street toilet in poland!