Each year, there are an estimated 16 million cases of acute gastrointestinal illness in the U.S. stemming from contaminants in community water systems.
New research in The Review of Economics and Statistics finds quick notification of water problems can help keep households healthy, avoiding millions of dollars in lost job earnings and direct health care costs.
The research shows that timing matters: Households noticeably change their behavior by purchasing bottled water, but only when notified immediately of potential problems with their tap water.
“People tend to think that the water coming out of their tap is treated and clean and safe to drink,” says author Michelle Marcus, a health and environmental economist at Vanderbilt University. “But it’s actually fairly surprising how often these health-based drinking water violations occur even in the U.S., where we have pretty good water quality.”
In November, for example, residents of Millwood, Washington, faced a boil water order for nearly a week after samples showed elevated levels of coliform bacteria.
In October, water at an elementary school in Honolulu tested positive for coliforms following several nearby water main breaks.
In September, residents in west Baltimore were told to boil water after officials there found coliform contamination, including E. coli, in samples.
While coliform bacteria are generally not harmful to humans, according to the U.S. Environmental Protection Agency, federal regulators long maintained that coliforms are a bellwether for disease-causing viruses, parasites and bacteria.
The Environmental Protection Agency requires that community water systems, which can be public or privately owned, conduct regular tests for coliforms.
The public must be notified within 24 hours of acute violations. Acute violations happen when public health is immediately at risk — for example, if a water system detects thermotolerant coliforms such as E. coli, which can grow at relatively high temperatures and often indicate water contaminated with human or animal feces.
E. coli live naturally in the intestines, but certain strains can cause gastrointestinal illness, ranging from mild diarrhea to nausea and vomiting, with the risk of kidney failure in rare cases in very young and older people.
Federal regulations allow local water officials to use a variety of methods to issue public violations, including the news media or postal mail.
Until 2016, federal rules also required that most community water systems notify residents within 30 days when 5% of their monthly samples tested positive for total coliforms.
“Total coliforms are a group of closely related bacteria that are natural and common inhabitants of soil and surface waters,” according to a 2015 Environmental Protection Agency guidance document for community water systems serving under 1,000 people.
As of 2016, the federal government no longer requires that water systems of any size notify residents of coliform violations stemming from regular sampling — so long as any indications of fecal contaminants fall below prescribed levels and the water system identifies and fixes the problem.
In its final rule, which was published in 2013 but did not go into effect until 2016, Environmental Protection Agency officials maintain that the mere presence of coliforms “by themselves do not indicate a health threat.”
But the recent research shows that when the public is not notified of coliform violations in a timely way, there can still be costly consequences related to purchases of over-the-counter remedies, hospital stays and lost time at work.
Immediate notification, less sickness
Waterborne pathogens that cause gastrointestinal illness account for $160 million in direct healthcare costs each year in the U.S., according to research published in January 2021 in the journal Emerging Infectious Diseases. The authors estimate an additional $2.39 billion in direct healthcare costs when people get sick from breathing contaminated water droplets — at a hot tub or spa, for example.
The new paper in The Review of Economics and Statistics explores how the timing of public notifications related to water quality issues affects household behavior.
Marcus focuses on coliform violations from 2004 to 2015 in North Carolina, because of the quality and detail of data available for the state. This period covers roughly the decade before the federal rule went into effect that made it so community water systems no longer had to tell the public about certain types of contamination identified during routine testing.
Acute violations — those arising from testing indicating an immediate health risk and requiring 24-hour public notice — led households in affected areas to increase bottled water purchases by roughly 78%, on average, during the month the violation occurred, Marcus finds.
Less severe violations related to routine testing — those requiring public notice within 30 days rather than 24 hours — did not, on the whole, affect bottled water purchases.
Marcus finds 60% of community water systems in North Carolina notified households of those less severe violations within one week. Yet for water systems that notified households within one day of less severe violations, bottled water sales increased 40% on average. Notifications sent beyond the first day did not affect bottled water purchases.
While the notification timing was available for North Carolina, the method of communication was “not systematically recorded,” Marcus says. But the research shows early notification of water problems can meaningfully change household behavior.
“The timing of information to the public really matters,” Marcus says. “That’s something that can broadly apply to many different violations for drinking water, and even violations for different types of pollution.”
Although most coliforms do not affect human health, Marcus notably links less severe violations — those that water systems typically took longer to communicate to the public — with more purchases of over-the-counter medicines for stomach distress.
That relationship was not evident for acute violations, indicating the uptick in purchases of clean bottled water following quick notifications helped people avoid sickness.
Hospital admissions were also linked to monthly violations, especially for school-aged children. Likewise, monthly violations were linked to school absences, especially for elementary school students.
Costs of delayed notification
Marcus figures the dollar costs related to immediate warnings about potentially harmful water compared with warnings that come later. If the public had been notified within 24 hours of all testing violations — even those that only required notification within 30 days — Marcus estimates bottled water purchases would have been $365,000 higher in North Carolina during the decade studied.
Marcus also estimates how much the violations that water systems were slower to communicate to the public cost residents in terms of medication purchases, hospital visits and time lost at work.
- Some $441,000 worth of over-the-counter gastrointestinal medicines were purchased due to coliform violations in North Carolina.
- Emergency department visits cost another $422,000.
- Assuming an average wage of $25 per hour and assuming one parent missed one work day for each day a student was absent from school, there were nearly $7 million in lost earnings over the decade.
These are, to be sure, “back-of-the-envelope” calculations, as Marcus writes in the paper. Considering the wages-lost estimate, for example, some parents will have paid time off and won’t have foregone earnings because their child missed school. Others might have nearby relatives to help.
Still, the rough total estimate of costs related to monthly coliform violations that were not immediately communicated to the public comes out to $7.7 million — well above the several hundred thousand dollars’ worth of bottled water that would have been purchased if the public had been immediately notified about every violation.
“The jury’s still out,” Marcus says, referring to the long-term effects of the Environmental Protection Agency’s decision to no longer require public notifications for less severe coliform violations. But, she adds, her research “does indicate that previous to that revision, we were observing health effects for even that monthly coliform violation, which was thought not to matter very much in terms of health.”
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