how long is a 1/2" diamater pipe that will hold 0.375 gallons of water?

Question

Energy code requires a maximum of 6 cups of water in a branch pipe to a faucet.  How long can a 1/2" I.D. be to meet the requirement?

Answer 1

pipe=cylineer, sol volume=pi*radius*radius*leng

=3.14159*.5*.5*leng or 0.7853982162*leng

but need tu konvert gallons tu sumthun bout inch

1 gallon=230.995130923 kubik inch

yu ask for 0.375 gallons...85.468198 kubik inch

so leng=85.468198/0.7853982162

=108.821 inches

or 9.0685 ft

Answer 2

The answer given cannot be correct.  they used the diameter times PI.

This answer is different from another site by a factor of 10.