We recommend only using purified or filtered water since the VitaBead Diffuser does not filter water. However, any water you consider safe to drink, you may use with the DYLN Bottle. For example, your tap water quality may be a different drinkable standard quality depending on where you live. The DYLN Bottle will enhance any water you add to it, however, it will not filter water. As for water temperature, we do not recommend using hot or boiling water as it will decrease the lifespan of the VitaBeads. Using warm, room temperature or cold water is fine.