Megadroughts Are Here To Stay, And U.S. Water Utilities Need To Adapt

By Christian Bonawandt

Historically, the West Coast has oscillated between intervals of wet and dry weather, with each lasting for several decades. However, new research from the University of Colorado Boulder shows that the current dry spell is not going anywhere any time soon. As a result, researchers warn that California and other states affected by megadroughts — periods of drought lasting 20+ years — will have to accept this as the new normal. That means rethinking the water cycle and finding new, more sustainable water sources.

‘Accelerating The Natural Water Cycle’

Municipal leaders in these drought-stricken regions are looking for ways to expand water portfolios by tapping into new resources and using current ones more effectively. According to Dr. Adam Zachies, vice president and reuse practice lead at Brown and Caldwell, one way utilities aredoing the latter is by “accelerating the natural water cycle” is “by taking water that historically goes to the ocean in forms of wastewater effluent and capturing that water.”

Southern California has been working on this for years, using advanced water purification (AWP) technology to treat wastewater so it can be injected back into aquifers and other water sources used for drinking. Also known as indirect reuse, this bypasses the need to wait for water to evaporate from the ocean and precipitate down to replenish drinking sources, effectively creating a new water cycle.

Guidelines for AWP are enshrined in California’s updated Title 22 regulations. More recently, Arizona has adopted its own AWP rules, loosely modeled off of California’s. In both cases, AWP is defined as a multi-barrier system that includes both pathogen and chemical removal. Typical treatment trains use microfiltration or ultrafiltration membranes, followed by reverse osmosis (RO), with UV advanced oxidation process (UV-AOP) on the backend. However, other types of AWP may use combination of granular activated carbon (GAC), ozone and other processes depending on the situation.

Beyond reuse, another critical strategy is to access water sources that may not have previously been considered viable. For example, water that is excessively turbid or brackish can be treated to meet drinking water standards using commonly available technologies. “Before maybe we wouldn't use that water, but now we're trying to take advantage of all possible water supplies,” Dr. Zachies said.

An Ocean Of Opportunity

The prospect of another 20 years of drought conditions is also renewing conversation about the viability of desalinating seawater for drinking, particularly with RO. Ruben Munoz, lead practitioner of desalination at CDM Smith, notes that while many coastal cities have already begun to employ this technology, it is also being looked at by communities further inland, even if it means pumping water hundreds of miles. “Hopefully in the future you will see the cities located on the coastline building bigger capacity with plans to pump it inland to areas where the river or the groundwater is not sufficient,” he said.

While the capital and pumping costs for such large-scale projects are significant, Munoz noted, the cost of inaction or the absence of water is far higher. In some places, such as Australia and the Middle East, the high energy consumption associated with RO and desalination remains is offset with solar and other renewable power sources. Other advancements have been aimed at mitigating costs, including modular solutions for construction, the development of higher-capacity energy recovery devices, and compact membrane designs that lessen the need for extensive infrastructure.

However, the long lead times for these projects — whether AWP or desalination — remain a considerable hurdle; some plants take up to 10 years to move from planning to operation. To make the process easier, Dr. Zachies advises relying on planning fundamentals, including clearly defining the size and benefits of the project. He added that projects like these often have a lot of groups involved in the outcome. “So, you have to do a lot of stakeholder engagement, understand what their needs, their roles will be on the program,” he said.

Christian Bonawandt is an industrial content writer for Water Online. He has been writing about B2B technology and industrial processes for 24 years.