The amount of water lost and the number of days are proportional — the longer the leaking, the more water will be lost. If we increase the time “x” times, the amount of water will increase “x” times too. That said:
If the amount of time increased 5 times (1 day to 5 days) then the water will increase 5 times:
5 * 2.25 (or 2 1/4) = 11.25, or 11 1/4 inches of water is lost over 5 days.