Question 115112: how much water is needed to fill a tank 15feet long,9feet wide and 3 feet deep.What is the formula and answer please. Ineed help and so does my 10 year old daughter: how much water is needed to fill a tank 15feet long,9feet wide and 3 feet deep.What is the formula and answer please. Ineed help and so does my 10 year old daughter Answer by edjones(2391) (Show Source):