I am just new to brewing in the UK having done a little bit of it down under. However, I have noticed that the tap water tastes a lot different here, with more calcium in it. I was wondering, if that changes the taste of your brew? Last brew I put down, I used bottled water from Tescos. Does anyone recommend that

Last question, I often get foaming over during this first 2 days of fermentation. so I have started filling my brew only to 4 gallon mark, waiting for 2 days of fermentation then adding the rest of the water. Is this a good or bad technique?
Cheers,

Potatoes