Let's Have a Cup Of Tea

[BIAD]

I couldn't survive without tea.

Any strong black tea, but what I find that makes a great cuppa' is what kind of water you use.

Please explain, I've heard of this before, but being a working-class scumbag from 'up Norf' in England,
the quality of water issue alludes me. (My mathematical equation of water quality for tea begins with
the word 'wet'!!)