I am interested to know exactly where my house water supply comes from, i.e. which reservoir.

Is there a website that you can put in your postcode and it gives you the exact water source/s. I have searched with google but most websites just give a vauge answer (reservoir or ground water).

Ring the water company, they will tell you.

Mine comes from a bore hole that draws from the aquifer underneath, free mineral water out of my taps. Nice...

Simple, just pee into each reservoir, wait a week and see when you get the taste