Photo of purple pipes courtesy of “freshelectrons.”

Water is a precious resource that needs to be conserved, particularly in the semi-arid and mediterranean climates of Southern California. Although roughly 75% of the Earth’s surface is covered in water, only 1% of that water is potable (drinkable) water. The supply of potable water is dependent on many environmental factors: adequate snow fall, drought, climate change, etc. The natural variation in potable water sources occasionally produces shortages in our water supply.

Humans use potable water for many processes: clothes washing, electricity generation, crop and field irrigation, etc. Interestingly, not all of these uses require potable water. Oftentimes recycled water can be used as a substitute for potable water. California’s plumbing code mandates that recycled water flow through purple pipes. Many of your schools have either already installed purple pipes or they are currently doing so. This means that your school may already irrigate its landscape with recycled water!

So what is recycled water and how is it made? Modern plumbing systems use potable water to transport wastewater from our homes and businesses to a reclamation facility, like the Inland Empire Utilities Agency (IEUA). This wastewater is then put through a tertiary treatment process that mimics nature’s cleansing process. Solids are screened out of the wastewater in the primary phase of the treatment; then, in the secondary phase, the wastewater is subjected to an aeration process, where microbes and other bacteria are allowed to consume and dissolve the remaining organic material. Finally, in the third phase of the tertiary process, the water is filtered again and disinfected. The result is a highly purified type of water called recycled (or reclaimed) water.

To learn more about recycled water and purple pipes, visit If possible, schedule a field trip to the Inland Empire Utilities Agency to learn more about the water treatment process. While you’re here, you can check out the Chino Creek Wetlands and Education Park (Learn About Water ).

Here is a link for young students to learn more about the water cycle and the many uses of water: Learn About Water .