why do you HAVE to boil and cool it before using it? There are plenty of brewers that use rainwater or tankwater for their brewing, and not everyone bothers with boiling it first.
Is there are known problem with your water?
All honest questions....
Whilst i usually use tap water to brew with, i have done (very recently) a brew with my tankwater which is coming straight off my roof, and to date, it is probably one of my best brews yet. Moteuka Pilsner, mmmmmmmmmm. Yummy.
No boiling and cooling here. Literally just filled some buckets from my tank and poured it into my HLT. Yes it initially smelt a little funny, but at the end of the day, the finished beer is beautiful.
Those pedantics amongst us who get right into water profiles etc...will probably chime in soon with their opinions and tell you to use some brewing salts, but i haven't bothered with it yet.
To be honest, the only reason i tried it like this first, is because the wife and i want to relocate the water tank to a different location at our house, and i thought, why not put it behind the shed (brewery).
"Better do a brew with it first to see how it goes"... i said to myself.