cooling wort

Hi, I have a 25l stock pot as my kettle for the boil of my brews. Once I'm done, I make an ice bath in the sink, whirlpool my hops, and cool down the wort through that method for pitching. It's not the fastest in the world, but it means a low cost suloution for me for now. What I wanted to ask...

Just a warning. I’ve been using freezer blocks and frozen PET bottles to cool the wort after boil for quite a few brews with no problems. This time however the tops of the freezer blocks came loose on two blocks. Not sure if any of the contents leaked out so I’ve had to ditch the brew arrrgh.