Controlled Temperature for Storage at the source

 The distillers of hydrolates must be willing to care properly for the waters if they are to have value as a therapeutic commodity. Cool, constant temperature with minimal or no light and sterilized dark opaque containers are best choices. Of course, cold storage is not always easy, but most distillers have some cool, dark facility for their oils. The idea temperature for the waters is around ten to thirteen degrees Celsius (fifty to fifty-five degrees Fahrenheit), and the consistency of the temperature range is important in preventing condensation inside storage vessels. 

Usually the dilemma becomes one of space. If you have only enough room for your oils in the cold store, are you really going to keep the waters? Is there enough value, both momentary and therapeutic, in hydrolates to justify the extra care they require? For many the answer is already yes, and for others it soon will be.

Reference: Hydrosols The next Aromatherapy; Suzanne Catty