Hi Joe,

I am not sure what units you want to use but measure the length of the pipe, $L,$ and the inside diameter $D.$. If necessary convert the measurements to ensure they are in the same units. The volume of water in the pipe, $V,$ is given by

\[V = \pi \; \left( \frac{D}{2}\right)^2 L \mbox{ cubic units.}\]

To calculate the weight of the water in the pipe you need to multiply by the density of water in the appropriate units. The density you need is in the units of weight divided by the units of volume you used above. Google will help with this. Type density of water into the Google search window.

I hope this helps. Write back if you need more assistance.
Harley