Tea leaves can be kept in a glass container, as long as they are kept in a cold, dark place, like a cabinet or cupboard. More importantly, the tea can be kept in the airtight containers by Nestasia to help prevent it from absorbing too much moisture, which can destroy the freshness and flavours of the tea leaves. Since glass containers do not permeate or absorb flavours, tea can be easily kept for an extended period in the glass containers.