T.B.
I used bottled water - room temp and mixed each bottle as needed. You can warm up the bottle by placing it in a hot glass of water. I used playtex bag bottles when she was little and switched to ventaire when she got bigger. Hope this helps. Also, my oldest was on enfamil and had constipation too so I switched to Nestle Good Start - she was great - no problems - I had my second daughter on Good Start too and she had no problems - my cousins also used it at my suggestion. My husband was annoyed that I switched formula without checking with the doctor - I explained that she was our daughter and the doctor was their to guide us - and don't fool yourself - it's a matter of preference with the doctor maybe even a kick back or two - who knows - you know your baby better than anyone and always trust your insticts.