#SummerScienceFriday | Energy-Water Nexus Series: Saving Water and Energy

July 26, 2019

In the first part of our Energy-Water Nexus Series, we explored the interdependent relationship between energy and water in our water supply system. We discovered that water travels over hundreds of miles before it reaches our taps. The Mediterranean climate of Los Angeles means it rarely rains, and we rely heavily on imported water. Typically, energy-intensive systems are used to transport water from the State Water Project, the Los Angeles Aqueduct, and the Colorado River Aqueduct to our homes, emphasizing the importance of conserving water and energy (1). This week, we investigate what goes on during the transport of our water from source to tap, and the ways we can conserve energy and water once it gets to our homes. 


If our water sources are natural, why and how is our water treated?

While the sources of water are very pure, it collects sediments and organics along the water and must be treated before it is safe to consume. Because of this, water is treated using conventional treatment including coagulation, sedimentation, filtration, and disinfection. After treatment, water is distributed through pipes leading to homes and businesses. Purple pipe transports recycled water for non-potable (non-human consumption) uses like irrigation.



Coagulation is the process of adding iron or  aluminum salts to the water. These salts, known as coagulates, have a positive charge and neutralizes the negative charge of the particles in the water. Those particles bind together (flocculation) and quickly sink and settle at the bottom of the water supply. Sedimentation is the process of these particles settling. Although these processes are a crucial step in the water treatment process, it does not remove all viruses and bacteria. Disinfection is the addition of chemicals, most commonly chlorine, in order to produce water safe for consumption (2). Chlorine has proven to be effective against most bacteria and viruses, easy to implement, and cost effective. It kills pathogenic microorganisms by disrupting cell respiration and DNA activity. UV disinfection can also kill pathogens by zapping them with UV rays (3). 


After you use your water, wastewater is transported to water reclamation plants to be treated. The five wastewater treatment plants in our watershed are: 1) the Hyperion Plant, 2) Tillman Plant, 3) LA Glendale Plant, and 4) the Terminal Island Service Area Plant. After wastewater treatment, the water can be either used for non-potable uses or released into the LA River and eventually the ocean (4).


Water treatment and energy conservation using sustainable landscapes

Conventional water treatment is extremely energy intensive but safe water is paramount. While we don’t have much control over that part of our water supply process, we do have control of how we use water and energy in our homes.


Sustainable landscaping is less energy intensive and can be used to conserve energy and treat runoff from our homes.These landscapes include planting trees, shrubs, and groundcover plants to shade and cool air before it reaches your home. In addition, you can also install water efficient landscapes. These include drought tolerant plants and stormwater management structures like bioswales, permeable surfaces, and vegetated depressions. These structures capture stormwater to increase infiltration and reduce runoff. Check out the Department of Energy’s Energy Saver infographic for more energy landscaping tips. Programs are available to help incentivize these energy efficient installations so check out the links below for how you can apply and get involved in minimizing your energy and water use. 


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