You need to know both length and circumference of the inside part of the pipe.
A 16" by 1,960' pipe holds 20,471.7 gallons water.
A 72-inch pipe 16 feet long holds up to 3,384.1 US gallons of water.
An 8" x 1,300' pipe holds 3,394.5 gallons of water.
100 feet of 3-inch pipe holds 36.73 gallons of water.
One foot of 3 inch pipe will hold approximately 0.625 gallons of water.
1.5-inch by 440 feet of PVC pipe holds 40.4 gallons of water.
The volume of the pipe is 0.2078 gallon per foot of length.I have no idea how much water might be in it.
A two inch pipe can hold 0.1632 gallons per foot. It takes slightly over 6 feet of two inch pipe to hold one gallon of water.
0.255 gallons per foot of pipe. A 10 ft long pipe that size holds 2.55 gallons.
The capacity of a pipe with a 54 inch inner diameter and a length of 120000 inches is 1,099,306,101 cubic inches, approx = 636,173 cu feet. There may or may not be any water in the pipe!
Depends on the diameter of the pipe and the speed at which the water travels through it.
Given enough time the entire ocean could be pumped through a half-inch pipe.