I found a detailed account of how someone uses water as a third pass of their CCO. I've been debating what to do with my left overs, so now I have something else to try before ditching it
Someone else had a variation...After draining the 2nd pass, the material is returned to the jar, which is then refilled with water and set aside. As a final step, and for a different product, we strain the water from the plant material, the same way we did the alcohol and cook it off exactly the same way. When the water is cooked off, we redissolve the remaining oleoresin in hot alcohol, and place it in the freezer for a couple of days, before filtering it. This time there will also be red waxy globs of insoluble material collected in the bottom of the jar. Cook off the alcohol, and it produces an oil that is more sedative that either of the first two extractions.
I just added water from the faucet shook it once lightly, and strained it off. The water absorbs the residual alcohol containing some target elements. It also changes the polarity so as to bring along more of the anthro cyanin pigments and is typically a bright red extract, though the color of anthro cyanins are affected by pH. The spent plant material is then discarded. We compost ours. I'm saying that after filtering and removing the water/alcohol, the end result concentrate is an interesting red color from water soluble plant color pigments. As far as usefulness, it recovers target elements, and reduces residual THC in the spent material, which in some locales is regulated for licensed facilities. I was introduced to the phenomenon by Jump 117 from Russia on IC Mag, and think it unique enough to pass on, but typically don't do it where time is of consideration, because getting rid of the water alcohol mixture is lots slower than just alcohol and higher temperatures are involved. A QWET concentrate is essentially (for practical purposes) the same as a winterized BHO from a content and utility standpoint. Both solvents dissolve what is in the trichome heads, and any differences lie in how the solvents were removed, which determines the levels of the remaining mono and sesquiterpenes. When I say the water extract is "more sedative", I mean that opposed to an energetic and "euphoric head high" typical of THC at the CB-1 receptors in your brain, you experience more "couch lock" sleeepy symptoms, typical of CBN. A good evening medication, but not a good choice first thing in the morning. If it is pain relief that you seek, I suggest extracting a higher CBD strain