Abstract
A study of water quality parameters was conducted in 38 small-scale roof-harvested rainwater barrels (RHRB) located in urban and peri-urban Philadelphia, USA in winter (November–December) 2014 and summer (June–August 2016). Parameters included two fecal indicator bacteria (FIB) (Escherichia coli and Enterococcus spp.) measured using culture-based methods, eight potential enteric and opportunistic pathogens (Campylobacter jejuni, Acanthamoeba spp., Legionella spp., L. pneumophila, Naegleria fowleri, Pseudomonas aeruginosa, Mycobacterium avium and Mycobacterium intracellulare) measured using quantitative polymerase chain reaction (qPCR), and two metals (lead and zinc) using inductively coupled plasma mass spectrometry (ICP-MS). Fecal indicator bacteria were detected in greater than 60% RHRB samples and concentrations (up to >103 per 100 mL) exceeded US Food and Drug Administration (USFDA) irrigation water quality standards. Among the enteric and opportunistic pathogens tested, 57.9, 44.7, 21.1, 18.4, 5 and 3% were PCR positive for Legionella spp., M. intracellulare, M. avium, Acanthamoeba spp., P. aeruginosa, and C. jejuni, respectively. N. fowleri and L. pneumophila were not detected in any sample. The concentrations of enteric and opportunistic pathogens ranged from 102 to 107 gene copies/L of barrel water. Lead and zinc were each observed in 88.5% of RHRB but the concentrations did not exceed US Environmental Protection Agency (USEPA) standards for irrigating produce, with the exception of one zinc observation (2660 µg/L). Based on these data, it appears that the risk associated with metals in RHRB is likely to be low, as these barrels are only used for gardening and non-potable purposes. However, risks due to fecal and opportunistic pathogens may be higher due to exposure to aerosols during gardening activities and produce consumed raw, and should be investigated further.
Highlights
As urban populations grow, corresponding increases in water demand have resulted in enhanced interest in alternative and decentralized potable and non-potable water resources [1]
Due to the lack of specific guidance on roof-harvested rainwater barrels (RHRB) water quality in the USA, the objectives of this study were to investigate potential public health risks through: (i) a characterization of fecal indicator bacteria (FIB), a range of potential enteric and opportunistic pathogens, lead, and zinc in barrel water; (ii) assessing the possible correlations between physico-chemical, survey, and rainfall parameters with the presence of FIB, potential opportunistic pathogens, and heavy metals in water samples collected from RHRB; (iii) determining potential exposures through a survey; and (iv) identifying potential risks through comparisons of contaminant concentrations with appropriate guidance or regulations
All thirty-four RHRB in the 2014 round and 2016 studies were constructed from polyethylene and all were used for gardening purposes (Supplementary Materials Table S1)
Summary
As urban populations grow, corresponding increases in water demand have resulted in enhanced interest in alternative and decentralized potable and non-potable water resources [1]. Many urban areas struggle to manage excess stormwater flows, and are served by combined sewer overflow systems (CSOs). CSOs can introduce untreated sewage into waterbodies during rain events. In the United States, the use of roof-harvested rainwater barrels (RHRB) for non-potable usages is gaining popularity as a way to address these concerns by alleviating pressure on centralized water and wastewater systems, practicing water conservation, and decreasing potable and non-potable water demand [2]. In urban developed areas such as Philadelphia, USA, residents typically do not rely on rainwater as a primary water source, but instead use it for non-potable purposes.
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