Camping-style cold brew tea

We used a sencha flavoured with banana, mango, melon, etc: https://tea.gr/eshop/caribbean-cocktail/ [https://tea.gr/eshop/caribbean-cocktail/] We left about two tablespoons of tea in 300ml of room temperature water for maybe an hour, then bought a bottle of cold water, emptied 300ml from it, and put...