No Chill Helles - Top up water?

[Moad]

I did a no chill Helles as a concentrated no chill (I only have 15L cubes). I will need to top it up with water prior to pitching, I am assuming tap water would be risky or may introduce flavours unwanted in a clean beer.

Should I use bottled water?

 

[manticle]

I'd boil some, cool and use that.