Gary Revoir, Vice President at Tetra Tech, shares insights on success metrics for recycled water, implementation challenges, shifting public perception and Tetra Tech’s solutions and contributions to the future of water reuse and recycling.

Gary ReVoir, Tetra Tech

Why should reuse be an embedded part of the water cycle?

The Earth has always recycled its water over and over for millions of years. Therefore, reuse has already been embedded in the water cycle since the beginning of time. What can be improved, however, is the quality of the reuse that is either being discharged to natural water sources, or even eliminated by diverting it to our drinking water sources. In order to make this a successful effort, the many ways we practice reuse can be improved and expanded by incorporating advanced water treatment technologies into the cycle.

In particular, limited water sources, growing restrictions on discharges, and fiscal constraints have moved the focus of the industry to view water reuse as an integral part of the One Water planning approach to developing the water cycle for a community. Water reuse projects are particularly effective in diversifying the locally-available water supply, while also reducing unwanted discharges to the environment. Reuse can be particularly helpful for utilities seeking a locally-controlled and drought resilient alternative water supply.

What are the metrics of success for recycled water? 

Broadly speaking, a successful water recycling program provides users with the water they need according to four major metrics: safety, reliability, affordability, and sustainability. Sustainability should be considered across the One Water Cycle, incorporating environmental resources and reinvestment of fiscal resources into water infrastructure. How each of these four metrics are defined, weighted and incorporated into the community’s One Water Program will vary significantly according to local regulations and the intended use of water, whether restricted access landscape irrigation, natural system protection or restoration, industrial reuse, groundwater replenishment, or even direct potable reuse.

“The key to reinforcing public confidence in water reuse is for utilities to work together to demonstrate the volume of freshwater saved, the environmental benefits gained, and the sustainability of our water supply by implementing more reuse.”

Much of society, as previously mentioned, is not aware that water has always been recycled. By introducing “planned” reuse without first laying the groundwork on the history of “unplanned” reuse, the process for acceptance and later, implementation will be much more effective and received with greater enthusiasm. By educating the community through science, technology and direct observation of the treatment process during thorough pilot-study cases, the public can see first-hand that planned reuse is a safe and reliable new drinking water source.

With today’s technologies, recycled water can be treated to meet the requirements of nearly any type of water use. Almost any need that could be supplied through traditional water sources can now be supplied with recycled water. A recent survey by Bluefield Research projected the volume of recycled water produced in the United States to increase 37% by 2027, from 4.8 billion gallons per day to 6.6 billion gallons per day. When you compare this against the nearly 30 billion gallons of water per day used in the U.S., you can see the potential for expanding water reuse. The issue that may limit wider application is making the connection between recycled water sources with existing and new water users. Key challenges include the cost of infrastructure, regulatory uncertainty, and public perception.

Challenges associated with the cost of infrastructure encompass both conveyance and treatment. Many regions have aggressively pursued public access irrigation as a water reuse option; however, this approach requires the construction of a second water distribution system in parallel with existing potable water distribution systems. While this may work in some suburban and rural environments, in urban environments it can be cost prohibitive to disrupt existing infrastructure to add a second distribution system. For other forms of reuse requiring a higher water quality, the cost of advanced treatment facilities can also present a barrier to implementation. However, when these challenges are examined and compared to the cost of doing nothing, and the multiple benefits of recycling and reusing water, the public perception of potable reuse is favorable.

In the United States, there is no uniform national regulation addressing water reuse, and regulations, if in place, vary widely from state to state. The approach to regulating reuse has been highly fragmented by state and type of application. As of 2012, there were 40 states with guidance on restricted urban reuse, but only 9 states with guidance on indirect potable reuse. While some states such as California, Texas, and Florida are beginning to look at regulations for direct potable reuse, the federal government has taken a more advisory approach towards regulations for reuse as evidenced by its history of publishing Guidelines for Water Reuse and the 2017 Potable Reuse Compendium.

Another challenge is getting users to adopt and require reuse, such as individual homeowners, agriculture, or large industry. Reuse ordinances can help incorporate irrigation into new residential development. In Monterey, California, the agricultural sector has been successfully been using reclaimed water since 1998 to grow cool-season vegetables. The risk of relying on a single large industry is significant, but a major user can infuse momentum and funds to build a local reuse program.

How can we shift public perception?

Public perception of water reuse has improved over the past 50 years, as water reuse has a demonstrated track record of safety and significant societal and environmental benefits. I think the key to reinforcing public confidence in water reuse is for utilities to work together to demonstrate the volume of freshwater saved, the environmental benefits gained, and the sustainability of our water supply by implementing more reuse. We need to continue to share best practices, success stories, and data. In the past decade we’ve seen an unprecedented volume of research and collaboration to help utilities move forward with their water reuse programs. The science is there to show that we can reuse water safely for all purposes, and no utility needs to repeat those efforts. That’s why organizations such as WateReuse and the Water Research Foundation are so critical for allowing the industry to make the most rapid progress without duplication of effort. I believe future generations will judge the expansion in water supply and environmental protection made possible through current developments in water reuse as one of the major innovations of our era.

We must be strategic about messaging though. Keep it short and to the point. Many people just want to turn on the faucet and know that the water is going to be there and be safe. While we can have the details available for those who want them, , the most important thing we can do is to continue providing excellent water service, day in and day out at a good value. That will build and keep public trust.
States such as California and Texas are already practicing planned reuse and have data that indicates the robust quality of the water they are producing. In Florida, there are dozens of utilities performing planned potable reuse pilot studies that have indicated likewise. Florida reuses 760 mgd for irrigation of lawns, golf courses, recreational areas, and providing water to industries. (maybe we don’t need the last sentence if question 3 is only for potable reuse.)

How is Tetra Tech leading with science to craft creative, cost-effective, sustainable solutions in water reuse?

Tetra Tech is Leading with Science® to deliver innovative water treatment solutions that bring exceptional value to our customers and we have been working with utilities to create the most cost-effective solution for investigating and/or implementing potable reuse by starting with the information and technology that’s already out there and has been proven. For many utilities investing in planned reuse, they are looking for long-term solutions to current and anticipated regulatory requirements. These current and anticipated regulations will require utilities to reduce their reuse discharges to the ocean or rivers, wetland protection and restoration, and surface water quality improvements Many utilities are also looking to become water-source independent. By leading with science, and not reinventing the wheel, Tetra Tech can provide proven, cost-effective solutions to utilities that can be implemented within their capital improvements programs. Expanding a water reuse system allows many utilities to meet different capital improvements or regulatory compliance and water supply issues, with one program. By Leading with Science®, Tetra Tech brings all of our expertise together to develop a solution that may meet multiple goals.

I’m especially excited about our ongoing work in potable reuse. One example is the 14.8 MGD Groundwater Reliability Improvement Program for the Water Replenishment District of Southern California, which achieves an exceptionally high water recovery of 92%, while including energy saving features that cut power consumption 17% below industry benchmarks, and an innovative UV/hypochlorite advanced oxidation process. In Florida, an example is the 3 MGD Groundwater Replenishment Program for the City of Clearwater; where we just completed the design and permitting of this innovative facility, which will be the first application of advanced technologies for indirect potable reuse in Florida. Working with the City, we identified, designed, and piloted an unprecedented, rigorous post-treatment process to stabilize the purified water for chemical compatibility with Florida’s sensitive aquifer.

What can utilities do, what is Tetra Tech doing / who else is contributing to this discussion?

Water managers will find the best results when they have an in-house champion that develops a vision for water reuse for the utility, city or county and then assembles a team who will develop the educational program on why water reuse is an essential component of the utility’s planning process, and the public benefit. Having an elected official as a champion at the policy level is an incredible advantage to the water managers, so I suggest to water managers to find that elected official. Again, I point water managers to the vast body of resources available from the WateReuse and the Water Research Foundation as a good starting point.

At Tetra Tech, we keep close tabs on the latest developments in public outreach and advanced technology to help our clients drive progress in the industry. For example, the City of Clearwater conducted a major public outreach program that including public surveys, townhall information meetings, project videos, a project website, and social media campaign to educate the public. On the technology side, one unique example is the City of Daytona Beach’s 200,000 gallon per day Direct Potable Reuse demonstration facility. This is one of the finest demonstration facilities in the nation with a fully integrated SCADA/PLC system, intended to simulate all the workings of a full-scale advanced water purification facility. In August 2018, the US Bureau of Reclamation awarded the City of Daytona Beach and Tetra Tech team a $400,000 grant to do cutting-edge work on “Tracking the Occurrence and Removal of Microbial and Toxic Hazards During Potable Reuse through Online Monitoring and Advanced Analytics.” We believe online monitoring technologies present significant opportunities to keep water safe from microbial and chemical risks and make treatment more intelligent and efficient.

The sky is the limit as far as water reuse is concerned. There’s boundless potential for innovation in technology, materials science, and energy efficiency. We’re already seeing online monitoring technologies that allow near real time bioquantification and toxicity testing. Better membrane materials are coming that will allow increased flux, reduce cleaning requirements, and curtail the need for chloramination, thereby reducing DBP formation. We are already seeing a first wave of UV-LED technologies that could radically transform UV disinfection and UV advanced oxidation processes. There’s an observation called Haitz’s Law (considered the LED counterpart to Moore’s Law) which notices that the cost of LED lumens drops 50% every 28 months due to underlying advances in semiconductor technology. Within the next decade, I expect we’ll see a revolution in UV disinfection and advanced oxidation as completely new applications and approaches for UV become possible.

What data do we have so far?

There is over 30 years of historical data available for the use of reclaimed water for meeting non-potable water demands, such as irrigation with a non-potable water supply produced from highly treated tertiary WWTP effluent. Decades of information is available related to both the water quality and not surprisingly, NO recorded health or public safety incidents.

As I mentioned before more than 4.8 billion gallons per day are reused for a variety of purposes in the United States, without any recorded adverse health incidents. There are more than a dozen full-scale potable reuse facilities in the United States, most have been practicing indirect potable reuse via groundwater recharge or surface water augmentation.

One of the most significant investigations was a long-term public health study by the Rand Corporation in 1999 in Southern California reviewing epidemiological data for adverse birth outcomes from 1982-1993 in areas where groundwater recharge had been practiced, compared to a similar population in Los Angeles County not receiving reclaimed water. The study found no effect from groundwater recharge on birth outcomes.

In Big Spring, Texas, the Colorado River Municipal Water District has been operating a direct potable reuse process since 2015 with good results. There is even a building scale implementation of direct potable reuse at the Western Reserve Land Conservancy in Moreland Hills, Ohio.

In the past 30 years there been more than 40 demonstrations of potable reuse within the United States and even more internationally. Denver Water conducted a landmark Direct Potable Water Reuse Demonstration project from 1979 to 1993 that included an extensive in-vivo biological testing program that showed the safety of purified water. Within the past several years at least four states have run pilot programs to produce great tasting purified water, wine, and beer (Clean Water Services, OR; Hillsborough County, FL; Arizona Pure, and Denver Water). The bottom line is that planned water reuse has rapidly grown over the past decade to demonstrate its ability to protect public health from acute and chronic health effects, while becoming a cost-effective option for developing alternative water supplies and completing a better water cycle.

What are Tetra Tech’s goals for the coming 12-18 months?

Tetra Tech’s goals for the next 12 – 18 months is to continue our involvement in the municipal and industrial industries to increase awareness of the benefits of water reuse, as well as assist in increasing the understanding of the regulatory and technological improvements needed to meet the current and future challenges anticipated for implementation.

Gary ReVoir will be speaking at World Water-Tech North America on a panel discussing Securing Future Water Supply through Water Reuse and Recycling on Thursday October 25 at 16.30.

To learn more about Tetra Tech, visit or follow on Twitter @TetraTech@TetraTech