Purple pipe is for recycled water that is not potable—meaning not for drinking. The water has been cleaned just enough so it can be used to water outdoor landscapes, golf courses, nurseries that grow plants you don’t eat, car washes, etc. The most popular use of reclaimed water is for irrigation.
The quality of recycled water can vary widely. So if you are lucky enough to have reclaimed water available to you for use in your garden, watch your plants closely as they adjust to the new water source.
Certainly, recycled water has emerged as a partial solution to California’s long-running drought. In San Diego, officials require that new developments that are close to purple pipes must connect to the city’s system.
Recycled water has been around for many decades. Los Angeles County has used it in its parks and golf courses since 1929. San Francisco built its first recycled water facility in 1932. Treatment of wastewater has advanced technologically over the years, to the point where some communities mix reclaimed water into the drinking supply via such methods as reverse osmosis and ultraviolet disinfection.
I was recently asked about the history of the funny-colored pipe. When water districts began recycling water, they needed a way to distinguish the difference between drinking water and water that was unsafe to drink. They did not have a lot of colors to choose from, with many colors already spoken for including blue (drinking water), green (sewers), yellow (flammables), orange (telecommunications), red (electrical) and white (planned excavation). So when the Irvine Ranch Water District–one of the southern California pioneers in dual distribution—needed to pick a color, that funny shade of purple/pink/lavender spoke to the engineers. It is now called Irvine Purple and has been deemed the standard recycled pipe color by the American Water Works Association.
Ideally, two water pipes would carry water to each home, farm, and business—one potable and one for recycled. The colored identifications make it easy to tell them apart.
For various reasons, this hasn’t come to pass as yet. Too much drinkable water is being wasted on gardens, when recycled water could do just as good a job, at a lower price, with less effect on the environment. Some water districts have made good strides trying to rectify this. It wouldn’t hurt to ask your local water officials about increasing their use of recycled water. We should all have a dual distribution system.