The water pressure of a sink has a steady flow of 2 cups per 10 minutes for the first 30 minutes. It still flows at 2 cups per 10 minutes for the next 30 minutes after. For the next hour, the water pressure maximizes to 4 cups per 10 minutes and stops. Shawn now has to dump half of the water away. How much water is left?
Please reason step by step, and put your final answer within \boxed{}.
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