Current Stormwater Harvesting Guidelines Are Inadequate for Mitigating Risk from Campylobacter During Nonpotable Reuse Activities

Abstract

Campylobacter is a pathogen frequently detected in urban stormwater worldwide. It is one of the leading causes of enteric disease in many developed countries and is the leading cause of enteric disease in Australia. Prior to harvesting stormwater, adequate treatment is necessary to mitigate risks derived from such harmful pathogens. The goal of this research was to estimate the health risks associated with the exposure to Campylobacter when harvesting urban stormwater for toilet flushing and irrigation activities, and the role treatment options play in limiting risks. Campylobacter data collected from several urban stormwater systems in Victoria, Australia, were the inputs of a Quantitative Microbial Risk Assessment model. The model included seven treatment scenarios, spanning wetlands, biofilters, and more traditional treatment trains including those recommended by the Australian Guidelines for Water Recycling. According to our modeling and acceptable risk thresholds, only two treatment scenarios could supply water of sufficient quality for toilet flushing and irrigation end-uses: (1) using stormwater biofilters coupled with UV-treatment and (2) a more conventional coagulation, filtration, UV, and chlorination treatment plant. Importantly, our modeling results suggest that current guidelines in place for stormwater reuse are not adequate for protecting against exposure to Campylobacter. However, more research is required to better define whether the Campylobacter detectable in stormwater are pathogenic to humans.

Assessment of Water Quality in Roof-Harvested Rainwater Barrels in Greater Philadelphia

“…Additionally, uses and their relative frequencies are different for US populations compared to those from Australia [6]. C. jejuni is a fecal-oral pathogen that can be of concern for food crop irrigation or toilet flushing using rainwater [58]. Campylobacter spp.…”

A review on microbial contaminants in stormwater runoff and outfalls: Potential health risks and mitigation strategies

“…Recent studies reported high risks due to Campylobacter spp. through reuse of stormwater in the Netherlands (Sales-Ortells and Medema, 2015) and Australia (Murphy et al, 2017). These studies, however, only measured members of the genus Campylobacter to estimate risk.…”

“…The risks from potable and non-potable uses of stormwater in Table 3 varied substantially depending on the target pathogen and exposure scenario. Risks were considered highest for viral pathogens, in most cases exceeding risk benchmarks for potable and non-potable use with the exception of toilet flushing in some cases Murphy et al, 2017). The studies summarized in Table 3 indicate that potable and non-potable exposures to stormwater are likely to exceed water quality targets [e.g.…”

“…QMRA can be a useful tool for examining the potential human health risks related to rainfall events and can inform risk management practices (Bichai and Ashbolt, 2017). These assessments show that there are non-trivial risks associated with the use of stormwater resources to supplement water portfolios and in some cases guidelines are not sufficient to mitigate risks (Murphy et al, 2017). This is needed as stormwater harvesting areas can create new opportunities for comingling of potential animal habitats or reservoirs for animal fecal material and human recreational environments, where transmission of fecal pathogens can occur (Sales-Ortells and Medema, 2015;Petterson et al, 2016).…”

Hydrophilic trace organic contaminants in urban stormwater: occurrence, toxicological relevance, and the need to enhance green stormwater infrastructure

“…12,13 It has been known for decades that urban stormwater is a contributor to the impairment of water quality. 14 Thus, monitoring and management programs have focused on conventional stormwater pollutants such as total suspended solids (TSS), [15][16][17] nutrients, 15,18 pathogens, [19][20][21] metals, [15][16][17][18]22,23 polycyclic aromatic hydrocarbons (PAHs), 17,[24][25][26] polychlorinated biphenyls, 27 and certain pesticides. 28,29 While stormwater research has long concentrated on particle-associated pollutants, a review article by LeFevre et al 18 highlighted the importance of dissolved stormwater pollutants (mainly nutrients, toxic metals, and hydrocarbons) and identified a major lack of knowledge about hyphil-TrOCs.…”