The pervasiveness of lead in drinking water poses a significant public health threat, which can be reduced by implementing preventive measures. However, the causes of elevated lead in water and the benefits of lead in water avoidance strategies are often misunderstood. Based on experiences in the United States, this paper describes an oversimplified ‘lead in water equation’ to explain key variables controlling the presence of lead in drinking water to better inform public health practitioners, government officials, utility personnel, and concerned residents. We illustrate the application of the equation in Flint, Michigan and explore the primary household-level water lead avoidance strategies recommended during the crisis, including flushing, filtration, bottled water use, and lead pipe removal. In addition to lead reduction, strategies are evaluated based on costs and limitations. While these lead avoidance strategies will reduce water lead to some degree, the costs, limitations, and effectiveness of these strategies will be site- and event-specific. This paper presents a simplified approach to communicate key factors which must be considered to effectively reduce waterborne lead exposures for a wide range of decision makers.This article has been made Open Access thanks to the generous support of a global network of libraries as part of the Knowledge Unlatched Select initiative.

The failure of the regulatory community to protect the residents of Flint, Michigan, from prolonged exposure to hazardous levels of lead in their drinking water has drawn public attention to long-acknowledged weaknesses in the implementation and oversight of the U.S. Environmental Protection Agency's (EPA's) Lead and Copper Rule (LCR). This rule defines the roles and responsibilities of water utilities in reducing consumer exposures to lead-in-water hazards. Despite this regulation, water-related lead poisoning cases have been documented in cities determined to be in regulatory compliance. This article presents preliminary results from an ongoing study that documents gaps and weaknesses in the rule and its implementation, oversight, and enforcement. We detail how the original intent of the LCR to protect public health has been undermined by inadequate lead-in-water monitoring and public education, as well as weak regulatory oversight and enforcement. We summarize how these issues contributed to the Flint debacle and are still being perpetuated today in other municipalities. Finally, we discuss how these factors may be thwarting the prevention of childhood lead poisoning in the United States, and contributing to disproportionate environmental burdens on low-income communities. This review is timely, in that it may prompt public involvement in the U.S. EPA's ongoing review and revision of the LCR.

Flushing tap water is promoted as a low cost approach to reducing water lead exposures. This study evaluated lead reduction when prevailing flush guidelines (30 s–2 min) are implemented in a city compliant with lead-associated water regulations (New Orleans, LA, USA). Water samples (n = 1497) collected from a convenience sample of 376 residential sites (2015–2017) were analyzed for lead. Samples were collected at (1) first draw (n = 375) and after incremental flushes of (2) 30–45 s (n = 375); (3) 2.5–3 min (n = 373), and (4) 5.5–6 min (n = 218). There was a small but significant increase in water lead after the 30 s flush (vs. first draw lead). There was no significant lead reduction until the 6 min flush (p < 0.05); but of these samples, 52% still had detectable lead (≥1 ppb). Older homes (pre-1950) and low occupancy sites had significantly higher water lead (p < 0.05). Each sample type had health-based standard exceedances in over 50% of sites sampled (max: 58 ppb). While flushing may be an effective short-term approach to remediate high lead, prevailing flush recommendations are an inconsistently effective exposure prevention measure that may inadvertently increase exposures. Public health messages should be modified to ensure appropriate application of flushing, while acknowledging its short-comings and practical limitations.

Private wells are a critical drinking water source and are susceptible to contamination from flooding. Opportunistic pathogens (OPs), such as Legionella, are an increasing source of drinking water-related outbreaks, but are poorly characterized in private wells. Here we conducted a molecular survey of OPs in private wells and plumbing systems shortly after the 2016 Louisiana flood. Detection frequency of fecal indicators was not notably high (total coliform 24.8% and Escherichia coli 3.5% in 113 private wells) ten weeks after flooding. Gene markers of Legionella spp., L. pneumophila, and Naegleria fowleri were detected in 77.5%, 15.0%, and 20.0% of a subset of 40 homes that were tested specifically for these OPs, respectively. Legionella spp. varied from 8.4 gc mL⁻¹ to 1.8 × 10⁴ gc mL⁻¹ in first draw and flushed water. Positive detections and levels of Legionella spp., as well as positive detections of L. pneumophila, were correlated with total bacterial numbers (measured as 16S rRNA gene copy numbers), suggesting that total bacterial numbers could be an indicator of OP occurrence under the conditions of private wells, which usually do not have disinfection treatment installed. Further, Legionella spp. positivity in first draw water from cold and hot taps was associated with their detection in flushed water, suggesting that the well itself can be a source of OPs. OP detection was not predictable from total coliform, well characteristics, or observable well damage, but was associated with higher metals in flushed water resulting from plumbing corrosion. Given that the majority of Legionnaires' disease cases are sporadic, private wells merit greater attention as a potential source of exposure.