Sewage water is recycled for irrigation

Image: John Loo

Chances are you've seen roadsigns that say "Using Recycled Water" and if you look close enough, you might also see pipes painted purple nearby. This water is popular for freeway median irrigation use and on farms. How do we recycle sewage water? Isn't all water recycled? Where does our drinking water come from, and why is this recycled water not suitable for drinking?