Remember that there are 16 cups in a gallon.
The pipe leaks 1.5 cups each day, so in one week, or 7 days, the cup leaks 1.5 times 7 cups, which equates to 10.5 cups per week.
To find this number in gallons, divide 10.5 by 16.
This equals .65625 gallons per week.
Hope this helps!
~Chrys
