If the tap water in your home is safe to drink, you can use it to prepare your baby's formula. If you use bottled water, speak to your pediatrician about fluoride supplementation at six months of age.   Fluoride is a necessary mineral for encouraging dental health.  It is found in tap water, but not in bottled or well water.  Some commercial nursery water brands, however, do contain fluoride.  As many babies start cutting teeth around six months old, it is important that they get fluoride to support this process.