Cold water extraction is the process whereby a substance is extracted from a mixture via cold water. It is a type of fractional crystallization. The process generally involves taking a mixture of substances, dissolving them in warm water, and then rapidly cooling the mixture. The insoluble compounds precipitate out of the water, while the soluble ones stay dissolved. The solution can then be separated by filtration or decantation. This process works by exploiting the differences in solubility (with respect to temperature) of varying substances, such as with common opiate-derived drugs that have been mixed with common non-opiate based analgesics, which occurs in Tylenol 3 and Vicodin.[1]

The Hot Water Extraction (HWE) method, is a method used in chemistry for extraction and for "steam cleaning" (e.g. carpets. as listed by the IICRC to be the primary method for cleaning carpets. Residential, and Commercial). The pressurized hot water extraction (PHWE) process uses a combination of high water pressure for agitation, and hot water to increase reaction rate.