Cloudy ice is not a sign that your freezer is dirty. It is dissolved air that got trapped as the water froze from the outside in, and it is why bar ice looks like glass while yours looks like a foggy brick.

I went through three trays and a lot of bad advice before finding something that actually works.

What does not work

Boiling the water. I tried this for a month because it is the most repeated tip on the internet. It helps slightly and never got me past mostly cloudy. Boiling removes some dissolved gas but the directional freezing problem is still there.

Filtered water. Better tasting ice, no clearer. If anything, the difference is invisible.

Silicone trays with lids. Fine for ice, no help on clarity, and the lids crack after a few months in the freezer.

What actually works

Directional freezing. You need the water to freeze from one direction so the air gets pushed to a part you can cut off.

1. A small cooler with the lid off. Fill a cooler or a small insulated container with water and put it in the freezer with the top open. The sides and bottom are insulated, so the cold hits the top surface first. After about twenty to twenty four hours you get one clear block with a cloudy layer at the bottom.
2. Let it sit out for ten minutes so it releases from the sides, then turn it out and cut the cloudy bottom off with a knife. What is left is clear.
3. Cut into cubes with a serrated knife and store them in a bag in the freezer. They will stay clear.

The insulated container is the whole trick. Mine is a nine dollar foam cooler from a gas station, and it outperforms every dedicated ice mold I tried.

If you want a purpose built version

• Look for a directional freezing mold that has an insulated shell and an open top. They run twenty to forty dollars and they do work, as long as they match the cooler method in design.
• Skip anything that just looks fancy. A big silicone cube mold with a lid is a big silicone cube mold with a lid. It will make cloudy cubes.
• Size matters more than brand. Two inch cubes melt slowly and dilute less than standard cubes, which is the real reason bar ice is better.

Is it worth twenty four hours of freezer space for clear ice? For cocktails on a weekend, honestly yes. A clear cube melts slower and looks dramatically better in a glass, and it costs nothing but patience. If you just want cold drinks, a regular tray is fine and this whole article is not for you.

One warning: do not put a glass or ceramic container in the freezer for this. It will crack. Use plastic or foam.