It depends on the dimensions of the tube, but the question did not provide all of them.
One foot of 3 inch pipe will hold approximately 0.625 gallons of water.
The volume of water in a 4-inch diameter, 1-foot section of pipe is 0.6528 gallons of water.
A 12 inch diameter round pipe will hold 4.89 UK gallons or 5.88 US gallons per foot.
17,000 gallons
7,480.52 gallons for every inch of depth
0.212 331 gallons per foot.
16 and 7/8
10,408 US gallons.
1 acre = 43560 sq.feet. 1 foot deep water over an acre is 43560 cubic feet, which is 325851.4 gallons in 1 foot deep. If it is 1 inch deep (1/12 foot) then it is 27154.3 gallons in 1 inch deep.
The capacity of the tubing is 94.6 Imperial gallons, or 113.6 US gallons. There need not be any water in it!
A 24-inch diameter cylinder holds 23.5 gallons of water per foot of length/height.
36.83 u.s. gallons of water in 1 ft. of 30" pipe