Water Conditioning & Purification Magazine

Drinking Water, Downpours and Disease

By Kelly A. Reynolds, MSPH, PhD

Adverse health effects associated with heavy rainfall events have been documented globally. Seasonal rains are commonly identified as precursors to increased surface water and groundwater contamination potentials and a more taxed municipal treatment system. Many state and government agencies promote increased private-well monitoring or additional community water services but the simpler solution is found within the POU industry.

2019 weather predictions
On Valentines Day, the National Oceanic and Atmospheric Administration’s (NOAA) Climate Prediction Center announced that an El Niño climatic pattern in the equatorial Pacific is officially in effect. El Niño is a natural condition, presenting every few years and characterized by unusually warm sea temperatures that can impact global weather conditions. Typical El Niño years result in increased rain in the southwestern and southeastern US. Storm experts at Colorado State University, however, evaluated possible scenarios for the 2019 hurricane season in the Atlantic and estimate a weak El Niño, which typically means fewer hurricanes ahead.

An average hurricane season in the Atlantic presents 12 named storms, six hurricanes and three major hurricanes. CSU experts determined that the most likely scenario indicates eight to 11 named storms, three to five hurricanes and one to two major hurricanes.1 This is good news after a few rough years in the wake of hurricane Harvey in Texas, which set records in terms of flooding and was the second most costly hurricane in US history; Irma, which hit the Florida keys at record duration of speed and sustained winds (185 mph for 37 hours) and Maria, resulting in the deaths of around 3,000 people in Puerto Rico, as well as other devastating hurricanes.2

Although it is too early to make anything more than qualitative predictions, CSU experts say that Texas is most likely to experience a hurricane this spring, while Florida is most likely to be hit by a major hurricane. An initial quantitative forecast for 2019 will be issued on April 4.

Rainfall and disease
While hurricanes can cause vast devastation, milder precipitation events may also have a measurable impact on public health. Several recent studies show associations between rainfall events and illness in exposed populations. One study in New Jersey showed a statistically significant increase in hospitalizations due to gastrointestinal illness following heavy rainfall events for persons served by a municipal surface-water supply.3 The study looked at over 47,000 cases from 2009-2013. A positive association was also seen with people who drank from groundwater sources, but to a lesser degree.
Another study in Massachusetts looked at the relationship between extreme precipitation events and emergency-room visits for gastrointestinal illnesses. This study focused on areas with and without combined sewer systems. Combined sewer systems primarily transport wastewater to municipal sewage treatment plants but are also designed to catch rainwater and industrial wastewater. During periods of heavy rainfall or snow melt, the capacity of the municipal treatment systems may be exceeded, resulting in an overflow of these catchment basins to nearby land and streams that may be in contact with drinking-water sources.

Combined sewer overflows (CSOs) are a major public health concern for about 800 or more US cities.4 When comparing regions where CSOs impacted drinking water sources versus CSOs impacting recreational water versus no CSOs, the researchers found a statistically significant difference in the rate of ER visits only in regions where drinking water was vulnerable.5 In fact, GI-related illnesses increased by 13 percent for all age groups and 32 percent in the elderly. The elderly are more susceptible to GI illness due to an inherently weaker immune system.

These same researchers evaluated sanitary sewer overflows (SSOs) and GI-related ER visits from 2006-2007. Sanitary sewer systems transport wastewater from domestic, commercial and industrial activities, as well as some stormwater, to municipal treatment facilities. If these combined waste volumes exceed the capacity of the sanitary sewer, an overflow or backflow event occurs. SSOs differ from CSOs in that the latter are designed to carry large volumes of stormwater. Both, however, can release untreated sewage and industrial wastes into drinking and recreational water supplies.
In the Massachusetts study, 270 SSO events occurred in the study region, consisting of four counties located in the northeastern part of the state. The authors found a nine-percent increase in GI-related ER visits with the strongest association seen in children. Since not everyone with GI illness seeks medical attention, the association is likely higher than researchers are able to track.

Up to 75,000 SSOs are estimated to occur in the US each year.6 Some states do not require reporting of SSOs; however, in Massachusetts, utilities must report SSO events to the Massachusetts Department of Environmental Protection, but the public is not necessarily notified. In one instance, the public was not notified of a SSO event that lasted 13 hours and resulted in eight million gallons of raw sewage overflow into a local river. Although residents were later warned to avoid the water, these notifications were issued far from real time.7

Avoiding illness
Improvements in municipal water treatment are expected to reduce the impact of storm-related gastrointestinal illness. One study focusing on municipalities with untreated groundwater sources predicted that GI incidence rates will increase as much as 4.3 percent relative to predicted climate-change models.8 If utilities are slow to address treatment or infrastructure needs, precipitation-related illness mitigation is also expected to be slight (up to 7.8 percent). Conversely, aggressive treatment installations can have an impact on reducing illnesses by up to 83 percent. The question for consumers is how quickly will municipalities upgrade treatment works and infrastructure? History shows that such adaptations have been much slower than the minimally recommended replacement rate. Fortunately, POU devices offer the most effective method for rapid, consumer-controlled treatment solutions.

Given that rainfall, CSO and SSO events are not always accurately predicted and that information on recognized events may not reach the public in a timely manner, having consistent exposure safeguards in place is recommended. Consumers simply do not know when their water has been compromised. One community found that private drinking water wells are rarely tested, even after extreme flooding events and even when free well-water testing is offered.9 For example, following hurricane Florence, free well-water testing was offered to residents in North Carolina, where about 35 percent of the population relies on private wells. More than 30 percent of wells tested positive for coliform bacteria and 13 percent for E. coli, a fecal indicator organism. The presence of E. coli indicates clear contamination from fecal wastes and the potential for other fecally transmitted pathogens to be present. According the state health department, about two percent of wells in the region typically test positive for either coliforms or E. coli. While some officials lobby for forced testing of private wells, legislation is generally considered unlikely.

Ultimately, one study found that providing municipal water services to just 10 percent of private well owners could prevent nearly 3,000 emergency-room visits per year.10 A quicker, easier and more cost-effective intervention would likely be to supply POU devices to the private well owners. Although the health and economic impact of POU devices has not been fully assessed in these particular applications, the implication is that they would have a significant benefit to public health.

1. Klotzbach PJ, Bell MM. “Qualitative Discussion of Atlantic Basin Seasonal Hurricane Activity for 2019; 2018.” http://tropical.colostate.edu. Accessed February 17, 2019.
2. Milman O. “From Harvey to Michael: how America’s year of major hurricanes unfolded.” The Guardian. https://www.theguardian.com/world/2018/oct/15/us-year-of-hurricanes-extreme-michael-irma-florence. Published October 16, 2018.
3. Gleason JA, Fagliano JA. “Effect of drinking water source on associations between gastrointestinal illness and heavy rainfall in New Jersey.” Lee C-L, ed. PLoS One. 2017;12(3):e0173794. doi:10.1371/journal.pone.0173794.
4. US EPA. “Combined Sewer Overflows (CSOs).” https://www.epa.gov/npdes/combined-sewer-overflows-csos. Published 2018. Accessed February 17, 2019.
5. Jagai JS, Li Q, Wang S, Messier KP, Wade TJ, Hilborn ED. “Extreme Precipitation and Emergency Room Visits for Gastrointestinal Illness in Areas with and without Combined Sewer Systems: An Analysis of Massachusetts Data, 2003–2007.” Environ Health Perspect. 2015;123(9):873-879. doi:10.1289/ehp.1408971.
6. US EPA. “Sanitary Sewer Overflows (SSOs).” https://www.epa.gov/npdes/sanitary-sewer-overflows-ssos. Published 2016. Accessed February 17, 2019.
7. Potera C. “From One Set of Pipes to Another: Gastrointestinal Illness following Sanitary Sewer Overflows.” Environ Health Perspect. 2018;126(4):044001. doi:10.1289/EHP3225.
8. Uejio CK, Christenson M, Moran C, Gorelick M. “Drinking-water treatment, climate change, and childhood gastrointestinal illness projections for northern Wisconsin (USA) communities drinking untreated groundwater.” Hydrogeol J. 2017;25(4):969-979. doi:10.1007/s10040-016-1521-9.
9. “Few Wells Tested for Contamination After Major Flooding From Hurricanes.” PEW Charitable Trusts. https://www.pewtrusts.org/en/research-and-analysis/blogs/stateline/2018/12/14/few-wells-tested-for-contamination-after-major-flooding-from-hurricanes?utm_campaign=KHN%3A Daily Health Policy Report&utm_source=hs_email&utm_medium=email&utm_content=6. Published 2018. Accessed February 17, 2019.
10. DeFelice NB, Johnston JE, Gibson JM. “Reducing Emergency Department Visits for Acute Gastrointestinal Illnesses in North Carolina (USA) by Extending Community Water Service.” Environ Health Perspect. 2016;124(10):1583-1591. doi:10.1289/EHP160.

About the author
Dr. Kelly A. Reynolds is a University of Arizona Professor at the College of Public Health; Chair of Community, Environment and Policy; Program Director of Environmental Health Sciences and Director of Environment, Exposure Science and Risk Assessment Center (ESRAC). She holds a Master of Science Degree in public health (MSPH) from the University of South Florida and a doctorate in microbiology from the University of Arizona. Reynolds is WC&P’s Public Health Editor and a former member of the Technical Review Committee. She can be reached via email at reynolds@u.arizona.edu

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