There are 16 cups in a gallon
There are 7 days in a week.
Multiply 7 days by 1.5 cups.
7 x 1.5 = 10.5
Divide 10.5 cups by 16 cups
10.5/16 = 0.65625
The pipe is leaking about 0.65 (or 0.7) gallons per week.
If you have any further questions feel free to ask.
Hope this helps.
