Today i Learned.... you're not supposed to put BOILING water into a hot water bottle.
I have been using boiled water from a kettle my entire life, my mother before that, my grandparents, and so on.
We never ever had issues, but I have been using one a lot lately, 4 or 5 times per day, and it finally "melted" a hole and leaked while the hot water was inside, and it went all over me. Luckily I was wearing layers of clothes so was not injured. But wow, I never realised you're not meant to, and you're hot meant to use hot water from a tap either because of possible impurities.. you're meant to boil the water in a kettle or saucepan, then let it cool down.
I will buy a new one when I can and still use boiling water - this hot water bottle lasted 14 years so, it can't be all bad haha