Flooded Wells Can Affect Well-Owner’s Health
By Charles A. Job
The series of extreme weather events that the United States has experienced recently has drawn attention to groundwater and its role in the daily lives of millions of people and effects on their wells. While the seven years of drought in California and of other durations in other western states focus us on water shortage and groundwater depletion, the hurricanes and tropical storms of the US Atlantic and Gulf coasts bring attention to excess water and floods. Likewise, stalled storms or continuing rain across the Midwest raise concerns about flooding, groundwater usability and foregone crop planting cycles. Fundamental to all these circumstances is the need for safe water for drinking and a range of daily uses, like bathing and laundering. Extreme weather has resulted in floods affecting wells and their water quality, as well as the well-owner’s health, creating a need for well disinfection across the country.
Context from recent events
For the 12 months from July 1, 2018 to June 30, 2019, thirty-six states experienced storms that resulted in flooding significant in extent to be federally declared disasters. Some states had multiple flood disasters, with Kansas recording the most with four. The total state-disaster designation that included floods was declared 80 times during that recent 12-month period (FEMA, 2019). Some of these declared flood disasters were localized to several counties in a state, some included an entire state (as was the case with Oklahoma and others) and covered large multi-state regions, as occurred with the Midwest flooding that affected 835 counties in 28 states from March to June 2019 (NGWA, 2019).
Based on the results of an earlier detailed study of wells flooded by Hurricane Floyd in 1999 in 10 North Carolina counties, the number of domestic wells affected by floodwater in the flooded counties was up to 10 percent of the number of well water-supplied households in the counties experiencing flooding. These figures, based on one study, are not statistically representative but give an approximation of wells potentially affected by flood events. Clearly, not all wells in a county experiencing significant flooding will be in a flood zone, which will depend on the duration, amount of precipitation and topography. In the case of the flooding that occurred across the nation during the first five months of 2019, a worst-case estimate of up to 250,000 domestic wells (10 percent of 2.5 million households utilizing well water in the flooded counties) may have been affected by flood events during that time (NGWA, 2019).
An exact number of wells actually flooded is difficult to determine without extensive field observation over large areas. The well location relative to surface-water bodies, topography of the ground surface, geology associated with the wells, duration of rainfall contributing to flooding and soil moisture conditions prior to flooding will also affect the number of wells impacted. Extended coastal lowlands and broad glaciated plains may have larger areas of flooding under intense, long-duration rainfall since they are not deeply incised by stream valleys that move water more quickly downstream.
Principal concern: human health
The principal concern for flood impacts to wells and groundwater is the possibility of well contamination from floodwaters carrying pathogens and chemicals that can affect people’s health. Floodwaters can pick up these organisms and substances from the ground surface and waste-disposal areas, including coal-ash ponds, Superfund hazardous waste and hog farm waste sites (CNBC, 2017; Pierre-Louis, 2018; Murawski, 2018). Exposure to E. coli, coliform and other pathogenic microbes from human and animal fecal matter may occur following a major flooding event and result in acute illness that may have longer-term effects. Household, farm and small business wells situated in the broad flat or gently rolling countryside or near streams and ponds could be standing in water for several days, raising potential health concerns if the well is not properly maintained. Table 1 gives the percentage of well samples submitted that tested positive for fecal contamination from flood events. Except for the Hurricane Floyd storm event, the wells were not systematically selected but were sampled based on the well-owners’ concerns about their water supply. The results show that a significant percentage of wells were contaminated by flood water affecting well owners suspecting contamination of their wells.
Another significant issue affecting both drinking water supplied from groundwater and septic systems treating domestic wastewater during flooding is high water tables connecting septic systems to a water well (NCDHHS, 2018; Murawski, 2018). Septic systems are typically not damaged by flooding but can become filled with water and not work properly. Also, removal of flood debris by vehicles may damage drain fields, tanks and distribution boxes. Septic-system professionals should be contacted to inspect and service the system. With continued intense rainfall and flooding, the water level of the aquifer may rise as floodwater infiltrates the ground surface. If the groundwater level (water table) rises to or near the ground surface, it can hydraulically connect a septic system to the water well. Fecal waste and chemicals usually treated by a septic system and the soil zone around it may not receive treatment and be drawn to the well used for drinking water if the well pump is activated while the water table is high (NGWA, 2018).
If this condition or flooding around the well occurs, the well owner should have the well tested for fecal coliform and other bacteria that can cause serious illness. The principal waterborne diseases and contaminants in private wells include Hepatitus A, Giardia, Campylobacter, E. coli, Shigella, Cryptosporidium, Salmonella, arsenic, gasoline, nitrate, phenol and selenium. Well contamination can lead to gastrointestinal illness, reproductive problems and neuorological disorders with infants, young children, pregnant women, the elderly and immuno-compromised persons at greatest risk (CDC, 2015). Indicator tests for coliform are inexpensive, typically $30-35 per sample. The cost of waterborne illness can include lost work time, hospitalization and even death (Roos, 2010; Frenzen et al. 2005) Lost work time from serious waterborne illness may be as many as 18 days and hospitalization may be up to four days (Sur et al. 2009; Kaljee et al. 2017). A typical hospital stay in the United States costs about $2,000 per day (TC, 2019).
Protection through well inspection and disinfection
Protecting a private domestic well should start with regular inspection of the well, including the wellhead and area near it to observe that correct operation and conditions are present for safe groundwater supply. These steps include: checking for well casing and apron cracks; ensuring proper setbacks from buildings, wastewater facilities and other sources of possible contamination from microorganisms and chemicals; removing contaminant sources; checking for adequate air movement around equipment; observing correct electrical connections and determining whether any wellhead casing extension is needed to mitigate flood impacts. Inspection of a water well by a qualified water-well professional may cost from $80 to $325 based on the site and characteristics of the well (CWT, 2018).
Well inspections should be done annually. Well disinfection steps include well cleaning (MDEQ, undated) and then chlorination, the most effective means to destroy pathogens in wells and plumbing (NDDH, undated). Typical preventive disinfection may not be adequate for flooded wells to destroy pathogens in the well water due to the significant amount of contaminants and sediment that floodwater may carry into the ground (NGWA, 2002) and to biological films supporting bacteria that can grow on well casing and screen (Duderstadt, 2018). A qualified water-well professional performing the well cleaning and disinfection should also resample the well water and send the sample to a testing laboratory. A further resampling over three months should also be included, followed by annual testing. Well disinfection is best accomplished when the pump is removed from the well (Artiola et al. 2013). Table 2 describes more detailed steps in well disinfection. Cost for well disinfection/chlorination through a qualified water-well professional may run $500 to $1,000 based on size, depth and other well factors (Beitsch, 2018; Personal Communication, 2019).
Other options for well disinfection include continuous well disinfection, which may be specified by state regulations directing specific components and steps. Continuous well disinfection may include the following types and components (ODOH, 2018):
• Chlorine disinfection
— Chlorine solution tank
— Retention tank
— Method to inject chlorine into a retention tank for contact
— Cyst reduction filters
• UV disinfection
— POE device
— POU device
• Other types of disinfection
These continuous disinfection types may not return a flooded well to safe drinking-water use, especially if electrical power is not available because of storm damage to the electrical system. Shock disinfection may be necessary in those circumstances.
Intense rainfall and flooding from extreme weather events are occurring across many areas of the country and impacting private domestic wells with contamination. Consuming water from a well contaminated from fecal waste or pathogenic bacteria from floodwater or septic systems can be serious. The cost of prevention and/or disinfection is significantly less than the effects of illness. Regular inspection and, if needed, disinfection can be effectively done by a qualified water professional to safeguard the well and its owner’s health.
(1) Artiola, J.; Hix, G.; Gerba, C.; Farrell-Poe, K. 2013. What Well Owners Should Know about Shock Chlorination. University of Arizona, publication AZ1605, Sep. 2013. Page 4 of 7.
(2) Beitsch, Rebecca. 2018. Few wells after major flooding from hurricanes. The Salem News, Dec. 17, 2018. (Quoting Merritt Partridge, President, Partridge Well Drilling Co., Inc., Jacksonville FL) https://www.salemnews.com/news/national_news/few-wells-after-major-flooding-from-hurricanes/article_d0798100-dbdc-5adb-af98-1938c0944657.html
(3) Centers for Disease Control and Prevention (CDC). 2015. Overview of Water-related Diseases and Contaminants in Private Wells. https://www.cdc.gov/healthywater/drinking/private/wells/diseases.html.
(4) Clean Water Testing LLC (CWT). 2018. Well Water and Septic Inspections. www.cleanwatertesting.com/local-water-testing-services/well-septic-inspections/; Job, Charles. 2017. Responding to Flooded Wells; A sustainability Issue. Water Well Journal, Nov. 30, 2017. https://waterwelljournal.com/responding-flooded-wells-2/. (This compares to the inspection cost to a small community groundwater system serving from 15 to 24 service connections of $1,392. See: Contra Costa Health Services. 2014. Small Water System Fee Schedule. https://cchealth.org/eh/small-water/pdf/Fees.pdf)
(5) CNBC. 2017. Hurricane Harvey rains flood toxic Superfund sites in Texas. Sep. 3, 2017. URL: https://www.cnbc.com/2017/09/03/hurricane-harvey-rains-flood-toxic-superfund-sites-in-texas.html
(6) Duderstadt, Eric. 2018 Biological Water Testing. Water Well Journal, Oct. 18, 2018. https://waterwelljournal.com/biological-water-testing/
(7) Federal Emergency Management Agency (FEMA). 2019. Disasters; Total number of declared disasters: by State/Tribal Government and by Year. fema.gov/disasters.
(8) Frenzen, PD; Drake, A.; Angulo, FJ. US National Library of Medicine, National Institutes of Health. 2005. Economic cost of illness due to Escherichia coli O157 infections in the United States. Journal of Food Protection, Dec. 2005, 68(12), pages 2623-2630.
(9) Kaljee, Linda M.; Pach, Alfred; Garrett, Denise; Bajracharya; Deepak; Karki, Kshitji; Khan, Imran. 2017. Social and Economic Burden Associated With Typhoid Fever in Kathmandu and Surrounding Areas: A Qualitative Study. Journal of Infectious Diseases (Jul. 29, 2017) , Volume 218, Issue suppl_4, 10 Nov. 2018, Pages S243–S249. https://doi.org/10.1093/infdis/jix122
(10) Maine Department of Health and Human Services (NDHHS). Undated. Continuous Chlorination Disinfection System Installation Guidance. https://www.maine.gov/dhhs/mecdc/environmental-health/dwp/fit/documents/ContinuousChlorinationGuidance.pdf
(11) Michigan Department of Environmental Quality (MDEQ). Undated. Water Well Disinfection. Page 4 of 10. https://www.michigan.gov/documents/deq/deq-wb-dwehs-gwwfwim-section10_183036_7.pdf
(12) Murawski, J. 2018a. The amount of E. coli and fecal matter in NC wells has spiked since Hurricane Florence. The News & Observer, Dec. 24, 2018. https://www.newsobserver.com/news/business/article223328915.html
(13) Murawski, J. 2018b. Florence bathed NC in raw sewage. New figures show it was even worse than we thought. The News & Observer, Dec. 24, 2018. https://www.newsobserver.com/news/business/article223328915.html
(14) National Ground Water Association (NGWA). 2002. Field Evaluation of Emergency Well Disinfection for Contamination Events; Final Project Report. Prepared by Stuart Smith, Ground Water Science. https://groundwaterscience.com/resources/tech-article-library/102-field-evaluation-of-emergency-well-disinfection-for-contamination-events.html
(15) National Ground Water Association (NGWA). 2018. News Release: Potentially 730,000 private water wells affected by recent hurricanes in the Atlantic. Oct. 16, 2018. https://www.ngwa.org/detail/news/2018/10/16/potentially-360-000-private-water-wells-affected-by-recent-hurricanes-in-the-atlantic
(16) National Ground Water Association (NGWA). 2019. News Release: NGWA Reports over 2.5 Million Households on Wells Potentially Affected by Flooding in 1st Half of 2019. Jun. 12, 2019. https://www.ngwa.org/detail/news/2019/06/12/ngwa-reports-over-2.5-million-households-on-wells-potentially-affected-by-flooding-in-1st-half-of-2019
(17) National Ground Water Association (NGWA), 2019. Residential Water Well Disinfection Following a Flood Event: Procedures for Water Well System Professionals.
(18) North Dakota Department of Health (NDDH). Undated. Safe Water Information; Proper Well Disinfection. https://deq.nd.gov/Publications/MF/WellDisinfectionFactSheet.pdf; Nova Scotia Environment and Labour. Undated. Disinfection of Water Wells by Chlorination. https://novascotia.ca/nse/water/docs/DisinfectWaterWell.pdf
(19) North Carolina Department of Health and Human Services (NCDHHS). 2018. Health Officials Warn That Excessive Rains, Flooding May Cause Problems with Home Septic Systems. https://www.ncdhhs.gov/news/press-releases/health-officials-warn-excessive-rains-flooding-may-cause-problems-home-septic
(20) Ohio Department of Health (ODOH). 2018. Continuous Disinfection. https://odh.ohio.gov/wps/portal/gov/odh/know-our-programs/private-water-systems-program/water-quality-treatment/continuous_disinfection
(21) Personal communication, May 3, 2019, industry source.
(22) Pierre-Louis, K. 2018. Lagoons of Pig Waste Are Overflowing After Florence. Yes, That’s as Nasty as It Sounds. The New York Times, Sep. 19, 2018. https://www.nytimes.com/2018/09/19/climate/florence-hog-farms.html
(23) Roos, Robert. 2010. USDA estimates E coli, Salmonella costs at $3.1 billion. Center for Infectious Disease Research and Policy. http://www.cidrap.umn.edu/news-perspective/2010/05/usda-estimates-e-coli-salmonella-costs-31-billion
(24). Sur, Dipka; Chatterjee, Susmita; Riewpaiboon, Arthorn; Manna, Byomkesh; Kanungo, Suman; Bhattacharya, Sujit K. 2009. Treatrment Cost for Typhoid Fever at Two Hospital in Kolkata, India. Journal of Health, Population and Nutrition. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2928117/
(25) Trusted Choice.com (TC). 2019. How Much Does a Night in the Hospital Cost? https://www.trustedchoice.com/insurance-articles/life-health/cost-night-hospital/
About the author
Charles A. ‘Chuck’ Job serves as Regulatory Affairs Manager for the National Ground Water Association. He previously worked at the US Environmental Protection Agency as Groundwater Protection Supervisory Hydrologist and then as Drinking Water Infrastructure Branch Chief. At US EPA, Job also worked in regulation development, underground injection controland information collection. Previously, he worked for the Ohio Department of Natural Resources and Great Lakes Basin Commission and as a financial analyst for Fortune 500 companies. Job earned Master’s Degrees in environmental science (Miami University) and applied economics (University of Michigan) and holds the credential LEED BD&C through the US Green Building Council.