Quick and dirty plumbing related shapes.
Might not be 100% accurate, but that's what github is for, right?
To install these shapes on a Linux system:
$ mkdir -p ~/.dia/shapes ~/.dia/sheets
$ git clone https://github.com/jgillmanjr/dia-plumbing-shapes.git
$ cp -r dia-plumbing-shapes/dia-shapes ~/.dia/shapes/plumbing
$ cp -r dia-plumbing-shapes/dia-sheets/* ~/.dia/sheets