For the shower multiply the amount of water per minute by number of minutes:
10.6 x 7 = 74.2 liters.
Calculate volume of the tube and the amount of water in it:
35 x 40 x 120 = 168,000 cubic cm.
Convert to liters:
168,000/ 1000 = 168 liters.
Savings = 168 - 74.2 = 93.8 liters
