Data obtained from the Florida DEP 2013 Inventory Report.
A recent article in Slate ran with the attention-grabbing title “Thirsty West: Why Californians Will Soon be Drinking their Own Pee.” The article was motivated by the planned $142 million expansion of a water reuse facility in Orange County, which will increase the local district’s capacity to take wastewater and convert it into sterile, drinking-quality water. Over the past several decades, increases in water scarcity levels and water demand in cities with growing populations have led to the introduction of similar water reuse projects to help boost supply throughout the United States. At the same time, issues surrounding water reuse have surfaced in the popular press, focusing primarily on the “yuck factor” associated with reusing water for potable purposes.
But before referring to potable reused water as “pee drinking,” it is important to distinguish between two types of potable reclamation and to consider some of the processes involved in potable water reuse. Direct potable reuse (DPR) introduces reclaimed water directly into a potable water distribution system, while indirect potable reuse (IPR) releases reclaimed water post-treatment into natural surface water or groundwater sources as a means of augmenting freshwater supply. Both DPR and IPR require advanced tertiary treatment processes such as membrane filtration and reverse osmosis, but by discharging treated water into surface water or groundwater prior to reuse, IPR utilizes environmental buffers such as rivers, lakes, and aquifers, which have a natural capacity to further purify the water. The Orange County water reuse facility referred to in the Slate article employs IPR by transferring treated water via a 14-mile pipe to recharge basins in Anaheim, where the water percolates through the soil and feeds the county’s aquifer system.
Furthermore, DPR and IPR currently comprise a relatively small proportion of total water reuse in the United States. According to data that we analyzed from the National Water Reuse Database, only 1 percent of reused water during the period between 2005 and 2011 was treated for DPR, while 17 percent of total recycled water during this period went to IPR purposes, such as surface water or groundwater augmentation. Florida, one of the nation’s leaders in water reuse, currently has no DPR systems and allocated only 14 percent of its total reused water to IPR in 2013 (see figure). In fact, most recycled water goes to non-potable uses such as residential greywater, industrial cooling, and irrigation of crops, golf courses, and public access areas.
Despite rigorous treatment processes, research reinforcing the safety of reuse technology, and assurances of water quality by authorities at local levels, the “yuck factor” associated with public perception of potable water reuse is real. Survey-based studies have shown that public support for water reuse initiatives generally wanes as the likelihood of individual contact with reused water increases. “Toilet to tap” and “sewage beverage” have become popular slogans used by those in opposition to potable reuse. Additionally, although people often favor water reuse as a general concept, attitudes change when potable reuse projects become more tangible and are proposed in specific communities. And yet, as mentioned in the Slate article, these public perception hurdles are not immovable. Research has also shown that public acceptance of water reuse is higher when protection of water quality and public health is effectively communicated, when there exists a high level of confidence in public authorities, and when people are aware of water supply problems as well as the environmental benefits of reclaimed water.
So how can economics inform our approach to water reuse going forward? One interesting characteristic of recycled water is that it generates different levels of socioeconomic benefits depending on its end use, and these different end uses are associated with different required levels of treatment (and thus different costs of provision). For example, although people are generally willing to pay much less for water used to flush toilets or irrigate parks than for drinking water, investment in providing this lower-value recycled water may be economically justified if the cost of treating wastewater to greywater or landscape irrigation standards is much lower than the cost of treatment to potable quality.
Because the costs and benefits of recycled water are a function of its end use, the expansion of recycled water as an alternative to freshwater poses an unfamiliar challenge with regard to allocation efficiency. Water resource economists have studied the optimal allocation of freshwater of uniform quality that is appropriate for use across all sectors, in order to employ scarce water in its highest-value use. However, when water is available in differing levels of quality, as is the case with recycled water, it may make sense to avoid high-value uses, such as the augmentation of drinking water supplies, given the potentially high cost of recycling technology needed to treat water to drinking-quality standards. Instead, it may be optimal to treat the recycled water for use in a sector with less stringent quality standards, such as agricultural irrigation, even if the societal value of a unit of water in this sector may be lower. Furthermore, demand for high value uses such as potable water is heavily influenced by consumers’ acceptance of reused water as a source of drinking water versus other uses, and the opportunity cost of water reuse in relation to other water supply options, such as desalination.
In order to adopt water reuse practices as a cost-effective measure to confront future scarcity problems, more scientific research on reuse technologies as well as economic research on the costs and benefits of reuse is needed. In the meantime, Californians can feel confident that they won’t be “drinking their own pee” anytime soon, at least in any significant amounts.