A pilot study of close to 200 pet dogs in homes that use private wells as their main source of water found that at least two-thirds of those dogs were consuming water containing high levels of lead, arsenic, and copper.
“Our results confirm that a variety of heavy metals are detectable in well water via direct sampling of dogs’ drinking water. Local land use and household factors influence the levels of metals detected, and there is geographic variability in the types/levels of metals detected,” the researchers wrote in the study. “Drinking water toxicity from heavy metals and other contaminants can lead to both acute and chronic health conditions, including organ failure in dogs. Because previous and emerging research supports dogs’ role as sentinels of human health and wellbeing, heavy metal toxicity of drinking water should likewise be regarded as a concern for humans living in the same households and homesteads.”
Currently, approximately 15 million households in the United States rely on private well water, for which they are responsible for maintaining and regularly monitoring the water’s quality and safety. Prior research has shown that consuming water from private wells might not be safe, as they tend to have high levels of lead, arsenic, radon, and other contaminants, often at levels higher than the Environmental Protection Agency’s permissible limits for heavy metals. “People and animals who rely on unmonitored groundwater may be at higher risk of exposure to drinking water contaminated by sources including but not limited to landfill seepage, failed septic tanks, urban runoff, oil and gas extraction, and pesticide use. Several recent studies have linked elevated rates of human illness to the consumption of contaminated well water,” the study authors noted. “For most companion animals, drinking water is provided by the people with whom they live and is typically from the same source (e.g., tap) that those people use.”
Audrey Ruple, a Metcalf professor of veterinary medical informatics from Virginia Tech in the U.S., and colleagues analyzed the drinking water samples of 178 dogs who lived in one of these 10 states: California, Florida, Michigan, North Carolina, New York, Pennsylvania, Texas, Virginia, Washington, and Wisconsin. They tested the water samples for 28 heavy metals. Around 87% of the dog owners reported that their dogs were in very good to excellent health. However, 82% of them admitted that their dogs were developing health conditions of some kind, which were not genetic or hereditary in nature.
Despite the fact that the researchers found that two-thirds of the water samples had high levels of lead, arsenic and copper, only 16% of the dog owners had reported that they were aware of a potential leaching source like a septic drain field, home heating oil storage tank, pond or freshwater stream, cemetery, or shoreline or marsh being located within 100 feet of their well. More than half of them used plastic water pipes.
“This pilot study suggests that a low-burden method of testing drinking water via at-home sampling from dogs living in households served by well water is successful at detecting potentially harmful and toxic metals in the water supply. We further find that testing dogs’ drinking water enables us to easily capture data from diverse geographic regions, characterized by specific risk factors and sources of contamination,” the researchers concluded.
The study was published in the journal PLoS Water in August, 2025.