Nav: Home

Water conservation can have unintended consequences

September 13, 2017

Conventional wisdom dictates water conservation can only benefit communities affected by drought. But researchers at the University of California, Riverside have deduced that indoor residential conservation can have unintended consequences in places where systems of wastewater reuse have already been implemented, diminishing both the quantity and quality of influent available for treatment.

The researchers outlined their findings in a recent paper, which appears online in the journal Water Research, published by the International Water Association.

"Drought, and the conservation strategies that are often enacted in response to it, both likely limit the role reuse may play in improving local water supply reliability," wrote Quynh K. Tran, a UCR Ph.D. student in chemical and environmental engineering; David Jassby, associate professor of chemical and environmental engineering; and Kurt Schwabe, professor of environmental economics and policy.

In the past, recycled water was only applied to areas such as low-value crops and median strips, Schwabe said. Recently, however, it has been considered safe to drink provided it either undergoes multiple rounds of treatment to remove concentrations of salts, nutrients, and other contaminants, or is injected into the ground and pumped back out later.

The United States reuses between 10 percent and 15 percent of its wastewater. In regions like Southern California, where effluent flows from inland communities down the Santa Ana River Basin and toward the coast, indoor residential conservation can limit downstream water supplies.

"You often hear it never stops raining at a wastewater treatment plant, meaning the influent from households will continue to flow regardless of whether we're in a drought or not," Schwabe said. "It may be true that it will continue to 'rain,' but the quantity of flow can be severely impacted by drought and indoor conservation efforts, which has implications for the reliability of the system, especially when it comes to downstream or end users of the treated wastewater."

Schwabe added the problem is pervasive in linked systems of wastewater reuse.

"If people are taking fewer showers and flushing their toilets less frequently, simple water balance dictates there can be reliability issues surrounding the reuse of water in systems such as those we have in Southern California," he said.

Exacerbating the problem, as wastewater flows decrease, their levels of salinity and other pollutants increase. Higher levels of pollutants present significant challenges for treatment facilities that are not typically designed to handle "elevated concentrations of total dissolved solids, nitrogen species, and carbon," according to Tran, Jassby, and Schwabe.

However, the researchers said solutions to those problems are available.

"Cost-effective blending strategies can be implemented to mitigate the water quality effects, increasing the value of the remaining effluent for reuse, whether it be for surface water augmentation; groundwater replenishment; or irrigation of crops, golf courses, or landscapes," they wrote.

To develop an economic model by which wastewater can be treated in a more cost-effective way, thereby increasing its value, the researchers identified feasible wastewater treatment technologies and wastewater treatment trains either in use or available for potential use. A treatment train is a sequence of treatments aimed at meeting a specific standard.

"Our solution is based on a system of blending water," Schwabe said. "Traditionally, wastewater facilities have operated by the principle that all the influent is treated to the fullest extent possible. But depending on the sort of demand and regulations a treatment plant confronts for its effluent, managers may have the opportunity to be creative and achieve a much less costly outcome by treating only a portion of the influent with the most advanced technology and blending this with the remaining influent that has been treated but with a less advanced and thus lower-cost process."

Schwabe said while this research indicates indoor water conservation may affect the reliability and quality of water reuse during drought, the researchers are not suggesting people engage in less frequent conservation.

"These results highlight a central tenet of economics: that there's a cost with every action we take," he said. "Our results are intended to illustrate how different drought mitigation actions are related so agencies can plan, communicate, and coordinate in the most informed and cost-effective manner possible."
-end-
The research was funded by the United States Department of Agriculture and the Binational Agricultural and Research Development Fund, a U.S.-Israeli partnership.

The University of California, Riverside is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment has exceeded 20,500 students. The campus will open a medical school in 2013 and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Graduate Center. The campus has an annual statewide economic impact of more than $1 billion.

University of California - Riverside

Related Drought Articles:

Vinegar: A cheap and simple way to help plants fight drought
Researchers at the RIKEN Center for Sustainable Resource Science (CSRS) have discovered a new, yet simple, way to increase drought tolerance in a wide range of plants.
Lending plants a hand to survive drought
A research team led by the Australian National University has found a new way to help plants better survive drought by enhancing their natural ability to preserve water.
New rice fights off drought
Scientists at the RIKEN Center for Sustainable Resource Science (CSRS) have developed strains of rice that are resistant to drought in real-world situations.
Drought linked with human health risks in US analysis
A Yale-led analysis of health claims in 22 US states found that severe drought conditions increased the risk of mortality -- and, in some cases, cardiovascular disease -- among adults 65 or over.
A basis for the application of drought indices in China
The definition of a drought index is the foundation of drought research.
Under the Dead Sea, warnings of dire drought
Nearly 1,000 feet below the bed of the Dead Sea, scientists have found evidence that during past warm periods, the Mideast has suffered drought on scales never recorded by humans -- a possible warning for current times.
Forests worldwide threatened by drought
Forests around the world are at risk of death due to widespread drought, University of Stirling researchers have found.
How much drought can a forest take?
Why do some trees die in a drought and others don't?
Pressures from grazers hastens ecosystem collapse from drought
Ecosystem collapse from extreme drought can be significantly hastened by pressures placed on drought-weakened vegetation by grazers and fungal pathogens, a new Duke-led study finds.
Molecular conductors help plants respond to drought
Salk scientists find key players in complex plant response to stress, offering clues to coping with drier conditions.

Related Drought Reading:

Droughts (Blastoff! Readers: Extreme Weather) (Blastoff! Readers, Level 4: Extreme Weather)
by Anne Wendorff (Author)

Droughts (Pogo: Disaster Zone)
by Cari Meister (Author)

Droughts (Let's-Read-and-Find-Out Science 2)
by Melissa Stewart (Author), Andre Ceolin (Illustrator)

Drought
by Pam Bachorz (Author)

Drought And Heat Wave Alert! (Disaster Alert!)
by Paul Challen (Author)

The West without Water: What Past Floods, Droughts, and Other Climatic Clues Tell Us about Tomorrow
by B. Lynn Ingram (Author), Frances Malamud-Roam (Author)

Witness to Disaster: Droughts
by Judy Fradin (Author), Dennis Fradin (Author)

The Drought-Defying California Garden: 230 Native Plants for a Lush, Low-Water Landscape
by Greg Rubin (Author), Lucy Warren (Author)

The Drought: A Novel
by J. G. Ballard (Author)

The Drought-Resilient Farm: Improve Your Soil’s Ability to Hold and Supply Moisture for Plants; Maintain Feed and Drinking Water for Livestock when ... Systems to Fit Semi-arid Climates
by Dale Strickler (Author)

Best Science Podcasts 2018

We have hand picked the best science podcasts for 2018. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Why We Hate
From bullying to hate crimes, cruelty is all around us. So what makes us hate? And is it learned or innate? This hour, TED speakers explore the causes and consequences of hate — and how we can fight it. Guests include reformed white nationalist Christian Picciolini, CNN commentator Sally Kohn, podcast host Dylan Marron, and writer Anand Giridharadas.
Now Playing: Science for the People

#483 Wild Moms
This week we're talking about what it takes to be a mother in the wild, and how how human moms compare to other moms in the animal kingdom. We're spending an hour with Dr. Carin Bondar, prolific science communicator and author. We'll be discussing a myriad of stories from her latest book, "Wild Moms: Motherhood in the Animal Kingdom", covering the exciting, stressful and even sinister sides of motherhood.