the very best method we’ve found is the partial or directional freezing method. we bought a cheap Coleman cooler, fill it with water, stick it in the freezer, and let it freeze most of the way, but not completely. it freezes from the top down, all the impurities in the water stay in the water as the ice freezes. clear ice every time. just gotta chop it into cubes from there!
FWIW - Jeffrey Morgenthaler’s thoughts in “the Bar Book.” Final paragraph was more or less “buy distilled water and deal with close, but not totally clear.”
That set of comments by Morgenthaler is pretty silly. If you take filtered water, freeze it, and use it promptly, your drink will not be impacted in any way except visually. The reason to use clear ice is because it looks good, period.
I actually had this as a class assignment back in college for one of my engineering courses. I can’t remember if it was Fluid Dynamics or Heat Transfer, but I do recall that the key was to use distilled water and have the water constantly moving over the chilled/freezing element so that the ice slowly built up. It came out crystal clear, but was a PITA.
+1, I have been doing this for a long time. Happen to have an RO spigot in the house but it really doesn’t make a big difference. Man up with a bread knife and hammer and make some cubes! A cutting board in or by the sink keeps it from being too big a mess.
I use this method all the time. My cooler is pretty small and it will freeze about three inches down from the top in just a little over 24 hours. The whole thing will slide out easily and then I score it all the way around where the ice and water meet with a bread knife. Usually the top solid part will separate and then you score the cubes and use a mallet and it separates. Then cut again for individual cubes. It is really cool to have crystal clear ice even if its just for water.