Formula water

sap05e

What do you use for water for a 2 week old? We have been boiling water and storing it in a glass container in the fridge but DD is waking up screaming to eat now and it takes too long to warm! I've also noticed the formula is clumpy if I mix it while cold. 

We asked a nurse practitioner at our pediatrician's office if we should be boiling water and she said yes for the first 2 months. But other people tell me they use bottled drinking water. Does anyone else boil? How do you store?