It seems obvious that there is a very serious water shortage in the West (see LWS blogs on the Drought Monitor and CO River Basin Drought Conditions), so water conservation and water reuse are getting a lot of attention, deservedly so. What does reuse mean? In its simplest form: not all water that is used for municipal purposes gets consumed, much of the water delivered to homes and businesses returns to a water reclamation facility where the water is treated.

What happens to this water after it is treated? Historically, treated wastewater has been discharged to a stream and allowed to flow downstream where other water users divert, treat, and use this water. However, as areas grow but available water supplies don’t grow, and possibly even decrease, more and more water suppliers are controlling the treated effluent so it can then be reused. But does the general public want to, or is ready to, accept the reuse of treated wastewater? Because of public perception issues, as well as regulatory controls, the methods of reuse that have been used extensively are non-potable reuse for irrigation and indirect potable reuse.

Non-potable reuse for irrigation has been used extensively; it not only allows reuse of water that would otherwise just be discharged downstream, so it is an efficient use of limited water supplies, but it also reduces the stress on water treatment plants and the need to provide peak demands through the potable water supply system.

Indirect potable reuse uses an environmental buffer, such as discharge to a stream, storage in a reservoir, or infiltration into an aquifer with subsequent recovery of a similar volume of water, before the blended water is treated and re-introduced into a potable water supply system. An example of an indirect potable reuse system is shown in Figure 1.

Conversely, direct potable reuse by definition means treated wastewater is treated to potable standards and then provided directly back into a potable water supply system without an intervening environmental buffer. Treatment technologies exist to allow either direct or indirect reuse systems, as there are advanced water purification processes that can be added to water reclamation plants to actually transform treated wastewater into high-quality, potable water.  However, regulatory and public perception issues generally favor indirect reuse, if not completely disallow direct reuse.

Potable reuse standards are regulated by the states and not by any Federal regulatory mandates. These rules can vary by state but in Colorado reuse policies are developed by the Department of Public Health and Environment (“CDPHE”). Until very recently there has been no state regulation that straightforwardly addresses direct potable reuse. However, on October 11, 2022, the Colorado Water Quality Control Commission, by a unanimous vote, adopted new regulations related to direct potable reuse.

Under the new regulations water providers

• will be required to show they have the technical, managerial, and financial resources needed to successfully treat wastewater;

• will be required to show how they will remove contaminants in their watersheds before the water reaches rivers and streams; and

• wastewater to be used in a direct reuse system will require extensive treatment, including disinfection and filtration, to provide potable water and eliminate pathogens like viruses and bacteria, and remove drugs and chemicals to safe and/or non-detectable levels.

Even with these new approved regulations, there is still the public perception issue. The new regulations do recognize this as a major issue to the implementation of direct reuse and, therefore, the regulations require water suppliers seeking to implement a direct potable reuse plan to set up extensive public communication programs to show the public its process and to help educate residents about this new water source.

Water is both a precious and limited resource that we must use more efficiently, as it is imperative that supplies remain available and preserved for future generations. Potable reuse is a viable and environmentally friendly strategy for achieving improved efficiency. The new regulations are certainly a step forward, as indirect and/or direct potable reuse is essential to make the most efficient use of our scarce water resources. Therefore, it is necessary to promote collaborative efforts: combining technology related to treatment processes that can purify water to potable standards, with partnerships with regulatory agencies that can help develop regulations to protect the health and safety of the public, and then educate the public through outreach programs.

If you are in need of the development of reuse systems with either surface water, groundwater, or conjunctive use systems, LWS can help with your water supply development needs. Feel free to give us a call (303-350-4090) or email our team members.

Bruce Lytle          bruce@lytlewater.com

Chris Fehn           chris@lytlewater.com

Ben Bader           ben@lytlewater.com

Anna Elgqvist     anna@lytlewater.com

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