Does making green tea with cold water affect caffeine levels?

Question

When I make iced green tea I steep 3-4 bags in a pitcher of cold water in the fridge for about an hour. I know this brand normally has about 40mg caffeine per cup when steeped hot for ~4 min. How does the difference in preparation affect the caffeine in the end product, if at all?

Answer 1

Hot water has more energy, and will be more effective in  helping the caffeine escape the tea leaves. But cold water will also pull the caffeine out of the leaves, and after an hour most of the caffeine in the leaves will have seeped out into the water.

Keep in mind that when you brew the tea in hot water, most of the caffeine will have left the leaves after the first steep. That process is analogous to how coffee is decaffeinated.

About 40 mg per cup seems about right.

Answer 2

It would probably have less caffeine when made with cold water.