The cannabinoids aren't water soluable, and the alcohol will evaporate before the water does. Your best bet is to ADD fat of some kind. Butter, oil, margarine, whatever, melt it into the water slowly. Once it's thouroughly melted, because you decarbed your weed, the oils (thc, cbd, ext) will have merged themselves into the fat (because they ARE fat soluable). Then just stick the whole mix in the fridge for a few hours until the fat hardens, then just scoop it off the top, and you just made weed butter!
Edit: Dont forget to strain any weed particles out before cooling. Organic matter living in an anaerobic substance (such as fat) can cause spoilage and bacterial growth to appear
Imo butter would be your best fat since it will harden at fridge temps and make it easier to separate out of the water. Oil and Margarine have to be frozen then scraped off the top.
I usually run one Oz to on Lb of butter. So you can do some math and figure it out for yourself how much fat to use