Water Reuse in Agriculture: Disinfection Byproduct Formation, Plant Uptake, and Consumer Concerns

Agricultural water scarcity concerns are pushing farmers to find potential alternative water sources for irrigation of food crops. With any water reuse scenario, there are concerns regarding the presence of potential contaminants. Chlorination of reuse water is often necessary to achieve proper water quality for irrigation or processing purposes, but the treatment process can form toxic disinfection byproducts (DBPs). Coupled with treatment concerns surrounding reuse water, the acceptance of food grown with recycled water presents additional challenges to adoption. Consumer perceptions and concerns about the safety of recycled water have been well documented for drinking water reuse, but information about barriers and motivators for consumers’ willingness to eat food grown with recycled water is lacking.
In this work, reuse water contaminants and consumer perceptions were investigated. First, the DBP formation potential was determined for various agricultural reuse sources by conducting chlorination reactions. All three sources showed different DBP formation potential patterns. Toxicity-weighted formation potential was also examined, revealing that the most toxic compounds are likely to form in waters with high nitrogen and bromide content. Next, the potential for plant uptake of DBPs was evaluated. Lettuce was grown hydroponically with varying doses of DBPs. A significant reduction in biomass was found in lettuce spiked with DBPs. Plant tissue extractions showed DBP uptake in both the roots and shoots. Calculations of weekly consumption based on the maximum uptake of chloroform in lettuce shoots did not indicate the potential for adverse health effects.

Lastly, a survey of United States adult consumers was conducted to assess their knowledge and perceptions about eating food grown with recycled water. The survey asked participants about topics including recycled water knowledge, trust, and perceptions. Familiarity with recycled water, trust in governing bodies, and water quality assurance all influenced willingness to eat food grown with recycled water. Optimizing water use strategies by exploring alternative water sources and barriers to implementation can help inform water management decisions working towards achieving future food security.