Scarcity and drought concerns are many driving water utilities to adopt AWS solutions as part of rapidly transforming resilience and reliability programs. But as states and municipalities work to diversify their portfolios to ensure a reliable, resilient water supply, direct potable reuse (DPR) — when wastewater is treated to the extent that it meets drinking water standards and then is added into the drinking water supply — is coming up in the ranks as a subject of research and development.
DPR Gains Traction
The concept of using recycled wastewater to offset potable water demands is not new – parks and landscaping rely on non-potable reuse, as do industrial and cooling water applications. This year however, several states either have put forth a pathway to potable reuse, or are working on frameworks and needs assessments for implementation. On Jan. 1, 2018, Arizona issued a complete regulatory approach to direct potable reuse, joining Texas on a pathway to DPR implementation. Based on statutes issued in 2001, Arizona’s new regulations allow the state to offer permits to facilities that perform advanced treatment on reclaimed water to produce potable drinking water.
Similarly in March, California issued an expert panel report identifying the research that would be necessary to regulate direct potable reuse. For decades, the state has regulated a version of indirect potable reuse that allowed treated wastewater to be added to aquifers to mix with groundwater before being treated and added to the drinking water distribution system. The state recently provided similar guidance for surface water reservoirs and plans to release new regulations focused on DPR in 2023.
Texas permitted potable reuse during its 2010 to 2013 drought, with the Texas Commission on Environmental Quality continuing to accept applications and issue permits on a case-bycase basis today. Florida recently formed a Potable Reuse Commission to begin the process of developing their version of a comprehensive framework for potable reuse.
When polled on their plans to invest in new alternative water supply solutions, 11 percent of the Strategic Directions: Water Report survey respondents said it was “extremely likely” that they would develop direct potable reuse options – ranking it in line with other options such as surface water/stormwater harvesting, contaminated groundwater treatment and potable reuse (indirect salinity barrier) (Figure 1). Meanwhile, a little more than a quarter (26 percent) of respondents said investing in direct potable reuse was “somewhat likely.”
Figure 1: How likely is it that your community will develop new Alternative Water Supplies?
It’s not surprising that this type of reuse ranked fourth, given the capital commitments involved. The leading three options — non-potable reuse (53 percent), potable reuse (indirect groundwater, 47 percent) and surface water/ stormwater harvesting (42 percent) — all are less costly than DPR, which requires more complex treatment processes and operations that offer a higher level of public health protection.
Additionally, smart monitoring infrastructure such as smart metering and real-time controls/ data analytics will be critical to this effort because of the monitoring requirements that inevitably will be put in place once states begin to move to DPR. Implementing direct potable reuse will have a direct correlation to a greater demand for data collection and analysis in real time.
Challenges in Alternative Water Supplies
More than half (52 percent) of survey respondents state high capital costs are a major barrier to developing new AWS projects, followed by a lack of financing/funding, stakeholder support and high energy use/costs (Figure 2). These responses are not surprising, given the level of major infrastructure investment needed to make recycled drinking water a reality. But today, we’re hitting a critical mass and city, environmental and utility leaders have to talk about those programs and the importance of expanding them.
Figure 2: What are the biggest challenges your organization faces in developing new Alternative Water Supplies projects?
Traditional financing routes include low-interest loans through the federal government or grants and loans offered at the state level. These options have their pros and cons – primarily, loans need to be repaid, so they still will impact the rate base. Municipalities may be better served if they investigate new, innovative methods of managing rate impacts such as subsidies and alternative rate structures.
When looking at community support, the majority of respondents say their communities are most likely to get behind water conservation efforts such as groundwater replenishment, aquifer storage and water banking (Figure 3). Conservation is often the most popular option – not only is it the least expensive, but small steps toward conservation go a long way when implemented at the community level.
Figure 3: How would you rate your community’s level of support for the following alternatives to desalination?
This is followed by indirect potable reuse (73 percent), where treated wastewater is added back into the groundwater supply, and surface water/stormwater harvesting (73 percent). All in all, the fact that survey respondents believe their communities would show support for the majority of the suggested treatment options demonstrates awareness and understanding of their alternative water supply.