Every hot water bottle tells you not to use boiling water in it, but at the same time everyone I know who regularly uses hot water bottles uses boiling water from an electric kettle.

Used to know a girl with about half of the skin of a darker color, from face to toes, burnt by a water bottle burst when she was little. Still I regularly fill them with boiling hot water. Same for everyone I know. Sometimes we're just that stupid...

...but everyone does. I just let it go off the boil and then use it.

I do see that there are silicone ones available, those should take boiling water in stride (though you'd need to wrap them in a thicker cover to avoid boiling yourself...)

The article also says you shouldn't use boiling water and recommends just using hot tap water.