Volume of water that can be held by the tank is the same as volume of cylinder.
v cylinder = π × r² × h
From the question we know that,
h = 40 ft
r = 18 ft
Plug the numbers to the formula
v cylinder = π × r² × h
v cylinder = 3.14 × 18² × 40
v cylinder = 3.14 × 12,960
v cylinder = 40,694.4
The volume of water is 40,694.4 ft³
