Dr. Kelsey Pieper: Well water quality
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About 15% of the U.S. population drinks water from private wells, which are not required to meet federal water safety standards, and testing water in some wells has identified health concerns including lead, high nitrate levels, and bacteria.
On February 5, 2025, SciLine interviewed: Dr. Kelsey Pieper, an assistant professor of civil and environmental engineering at Northeastern University. See the footage and transcript from the interview below, or select ‘Contents’ on the left to skip to specific questions.
Declared interests:
Dr. Kelsey Pieper has received research funding from NASA.
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Introduction
[0:00:19]
KELSEY PIEPER: My name is Kelsey Pieper, and I’m a professor at Northeastern University. I look at safe drinking water in the U.S. with a particular focus on well water. We look at where you live and who you are and how that influences your access to safe water. So considering things like local geology and the resulting groundwater associated with that, construction methods, access to resources, and user behaviors.
Interview with SciLine
How many people in the U.S. use water from wells?
[0:00:52]
KELSEY PIEPER: Unfortunately, we don’t have an answer to that. The EPA estimates that around 15% of the U.S., around 43 million Americans, are supplied by wells. But the last time we collected data on that was within the 1990 census. There have been efforts to predict, extrapolating from that data, what numbers could be and—but again, those are just estimates. The interesting thing about well water that is often a big misconception, is we think of them to be rural drinking water systems in rural areas, farming, but really they exist in both rural and urban settings. It’s really where municipal water lines stop. And so, when you think about a city where their services end is where private wells begin. So, we do see a large population of well users on the fringe of cities, but in rural areas, we see a larger percentage of the population on well water. So, it’s a really diverse population and found in almost all states across the U.S.
What contaminants have been identified in U.S. well water in recent years, and what trends have researchers found?
[0:02:03]
KELSEY PIEPER: A lot of the knowledge that we have is not complete in well water because these systems are not regulated by the U.S. EPA, like municipal systems. Private wells are not included under the Safe Drinking Water Act due to their size, and so our information about them and the data collected is often really fragmented and sparse. So, we have really good data over the years, but really, most wells go untested. And when we do campaigns, they’re not usually holistic campaigns, where municipal systems will regulate over 90 contaminants and tests for them. We will typically see private wells being tested for microbial contaminants, inorganics, and maybe some pesticides, and there’s not as much known about emerging contaminants like PFAs. So, we know a lot, but we really need to know a lot more about private wells. But generally, we know that private wells struggle with microbial contamination—that’s probably the biggest issue, and that really has to go to the construction of them and maintenance of the construction and allowing surface water to enter the system.
What does research show about the prevalence of lead in well water, and what effects can lead have on the body?
[0:03:19]
KELSEY PIEPER: There is no safe level of lead exposure. And the group that we’re most concerned about are children under the age of six and pregnant women. Those are our most vulnerable populations. As for lead in well water, there’s been a lot of misconceptions about it, and that’s really because in municipal systems, there’s been a big emphasis on lead service lines, which are pure lead pipes, and these are creating a lot of problems in the U.S. for municipal systems. But private wells don’t have a service line because they’re not connected to the municipality. So, people think that there’s often not a lead problem. But what we’ve been doing, and what we’ve shown in Virginia, is when we have well water that has lead-free plumbing components, because lead-free plumbing components can contain a legal amount of lead, which was up to 8% until 2011, that lead-free content can actually be released into well water, because well water is often untreated and in some areas, corrosive. So, I’ve done a lot of work in Virginia with the Cooperative Extension program, and what we showed was one in five wells had lead above the EPA action level. To put this in context, everyday wells in Virginia had the same lead in water concentrations as residents at the height of the Flint water crisis. And so, comparing those two, it really speaks to the magnitude of potential problems with corrosion and wells, because they’re using groundwater sources that are potentially corrosive.
What kinds of bacteria have been found in well water, and what health risks come with them?
[0:05:01]
KELSEY PIEPER: Bacteria is probably the biggest problem that we talk about in well water because studies depending—and again, it’s very local in what you find—but generally, studies say anywhere from 30% to 50% of wells tested will be positive for total coliform bacteria. This bacteria indicates that surface water has gotten into the well and suggests that there’s structural integrity issues with your well. We also see that around five to 10% of systems test positive for E. coli, which indicates that there’s fecal matter in your water. And so that surface water that’s getting in actually is coming from a fecal source, and so this is obviously very problematic. These two bacteria are called indicator bacteria, because they indicate problems. We really need to take it a step further, and some we’re seeing more and more research in this space, but we need to look at pathogens, the pathogens that are causing people to become sick, things like cryptosporidium, salmonella, legionella, and the naegleria fowleri. And that work, again, because these systems are not regulated, those tests are expensive—we don’t see as much data on the pathogens, but we do see a lot of work being done on the indicators, which is telling people that they need to further investigate their systems to make sure their water is safe.
What impacts do natural disasters like hurricanes have on well water quality and how people use well water? Can you give any examples?
[0:06:29]
KELSEY PIEPER: When wells are flooded during a hurricane, they can be contaminated with surface water, and that surface water during flooding can have fecal matter in it, can have chemicals in it. And so, when your well has surface water introduced, that becomes really problematic. So, what we saw after Hurricane Harvey was that wells that were submerged were eight times more likely to have E. coli, an indicator of fecal matter in their well water when they were flooded, compared to not. And so, this is telling us what most people already know, and a lot of anecdotal information has said, is that flooding increases the risk of fecal contamination. But this is really powerful to have data on this because we’re able to inform policy and practices when we know the implications of flooding on private wells.
What has your research shown about how health departments can strategize immediately after flooding to meet community needs?
[0:07:28]
KELSEY PIEPER: We are currently funded by NASA to develop a decision support system for the North Carolina Department of Health and Human Services. Through years of collaboration, we’ve been learning more about their programming and the need for data-informed decision making. So after Hurricane Helene, we aggregated different data sets and provided analysis on which well using populations may be impacted and the number of users. This was really powerful because it gave them insights into areas that might be most impacted, that have populations relying on wells, and also the number of users that may need assistance. Providing that information allowed them to think about testing strategies, providing disinfection resources. In addition to providing data information, we also help them with educational needs. We created YouTube videos for them on how to disinfect your well. So these are 10-minute technical videos that walk residents through various disinfection protocols to help empower them to recover their own system. These videos have been watched by 1000 or so people and run for more than 76 hours, speaking to the importance of providing educational materials where residents are. We also worked with North Carolina Ground Water Association and the riverkeepers to design wellhead models so we could provide them to health departments so they could educate residents with a model on how to sample their well, how to disinfect, how to look for damage. And so through this decision support tool, we’re providing data and educational resources in collaboration with nonprofits and the health department with the overarching goal of empowering and equipping local health departments to better respond to well water issues after natural disasters.
Who tends to be most affected by well water contaminants after flooding?
[0:09:42]
KELSEY PIEPER: If you asked me a year ago, I would have said residents within a floodplain or in close proximity to a floodplain are the most vulnerable to the impacts of flooding, and this is because they are more likely to experience flooding being in the floodplain. And this really is attributed to my work with coastal flooding after hurricanes, but after Helene, which was a mountain flooding, my perspective changed. And this is because mountain floods are very different than coastal floods, and it has to do with how the flood waters come into the community. In a coastal flood, we see it goes over a wide area, because the area is flat and it rises, you know, feet to tens of feet, but in a mountain, it’s all being funneled into the valley. And so we see extremely high velocity water, and we can see a lot of damage in wells. And so again, in the floodplain, we see the most vulnerable. But then in mountain flooding, there’s also landslides, and there’s also trees that come down. So residents, not only in the floodplain but also impacted by landslides and other land disturbances, are also at risk of contamination issues because there’s more damage. We saw a substantial amount of damage after Hurricane Helene, due to the velocity of flood water and also the land disturbances uprooting septic systems and wells. So really in coastal we look at floodplains, but in mountains, it’s really associated with flooding and landslides and disturbances.
How can people test or treat their well water?
[0:11:32]
KELSEY PIEPER: To test or treat your well water, I would recommend engaging with your local experts. This can be your local health department or cooperative extension. These are professionals that regularly work with your neighbors to address similar challenges and concerns, so they will have an understanding of water quality in your area, treatments being used, and where and how to test your system. For testing, I typically recommend microbial testing because this is a common concern and problem faced by many well users testing for inorganics, things like lead and arsenic, because we do see them occur in private wells and pesticides or nitrates—if in your area, this is a contaminant of concern. As for treatment, I would talk to professionals, because treatments can be hard to decide on, because they’re highly dependent on what the homeowner wants—how much maintenance. Where and how much water do you want to treat? Do you want to have it at the kitchen sink or the whole house? What contaminants are you trying to remove? So, these are conversations that you can have with a water treatment professional to help you decide the best treatment solutions.
