This article is investigating the preparation of essential oil from the ether-containing plants of Juniper (Juniperus) and spruce (Picea) leaves by using the simple water distillation equipment. This water distillation method forms an essential oil with water vapor from plants of Juniper (Juniperus) and spruce (Picea) leaves based on Dalton's law of partial pressure, applicable for plants containing a large amount of ether oil where distillation temperature is not affecting product quality. Obtained essential oils are widely used in medicine, perfumery, cosmetics, and food industry. In addition, these essential oils possess different activities including antimicrobial, antiviral, and anti-inflammatory, which have different effects such as adaptogenic, antidepressive, disinfection, and wound healing, diuretic, and antipyretic.