Copper pipe is popular throughout America for use in domestic water (potable) plumbing systems. These use copper pipes to deliver both hot and cold water to each fixture or appliance in a building. They can also be drainage pipes. Appliances may include sinks, showers, toilets, tubs and dish washers. You can calculate the volume of water a copper pipe can hold using the formula for the volume of a cylinder.

Measure the inside diameter (I.D.) of the pipe using a tape measure. The diameter is the distance across the interior circle of the pipe measured through its centre. This is the most accurate way to calculate volume. If the pipe is part of an existing system and you cannot measure the inside, measure the outside diameter of the pipe. The outside diameter is the total width of the pipe. Using the outside diameter will give a volume measurement that is slightly higher than the actual volume. Divide the diameter measurement in half to obtain the radius of the pipe.

Measure the length of the pipe using a tape measure. If there are multiple bends and straight sections of pipe connected together, measure each length separately and add them all together to determine the total length.

Multiply the radius by itself. For example, if the radius is 2 inches, multiply 2 times 2 which is 4. Multiply this number by the total length of the pipe and then multiply that number by 3.14 (pi). This is the cubic volume of the copper pipe.