Hi! We recommend mixing with warm water to ensure it dissolves quickly, easily, and with as little foam as possible (although foam is totally safe for baby and normal!), but ultimately, you can use whatever temperature water baby prefers. If you do heat the water before, just be sure that it cools before feeding to ensure baby's safety.

Was hoping to also get a response to Shaya’s question!

Follow up question...will mixing while the water has just come of the burner (so was just boiling) harm the nutrients in the formula? I don't typically do it that hot, I mix with some room temp water before pouring it into the formula (which is then refrigerated until baby is ready), but I'm just curious because my husband keeps asking. 