Why Does Cannabis Need to Test Below 0.65aw?

by Megan Newton October 11, 2022

Water activity has been a staple measurement in other industries, but why is it important in the cannabis industry? And why do you need to remember 0.65aw?

Yes, cannabis biomass such as flower needs to test below 0.65aw to pass California compliance testing. But other than that, why else does it need to test below that?

Because 0.65aw is a safety threshold.

Past experiences have shown that 0.7 water activity units (abbreviated as "aw") is the point where bacteria and mold start to grow and reproduce at a high rate. Any cannabis biomass that has a water activity below 0.7aw will likely not grow any bacteria and mold; above 0.7aw will likely grow bacteria and mold.

So why is the California regulatory limit 0.65aw and not 0.7aw? It is likely because it's a reasonable value that balances maintaining product quality (for the optimal user experience) and minimizing the risk of bacteria and mold as much as possible. If the biomass is already at 0.7aw, the minimum amount of water needed for bacteria and mold growth has already been achieved and is likely to develop. The range between 0.65aw and 0.7aw provides a safety net before the right conditions are reached for bacterial and mold to grow and thrive in.

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