Unbound water at the surface of a cannabis plant that can promote the growth of bacteria and fungi. Most cannabis regulations limit the amount of unbound water in order to prevent the growth of bacteria, yeast, and mold. According to ASTM International, during cannabis storage, this activity should remain between 55 to 65 percent.
Measuring the water activity is a great way to test how likely the product will become contaminated with microbes.
Limit the amount of water activity to ensure that microbes don't develop in the moisture.