About half all all Maine households rely on private well water, one of the highest rates in the country. But most wells here haven’t been tested for contaminants. Among those that have, one in 10 has elevated levels of arsenic, state toxicologist Andrew Smith told me last June.
How likely is your well to contain arsenic? The state has updated its searchable public health data portal, so now you can see the latest contamination counts by town. I’ve listed them by the percent of wells exceeding the maximum level of arsenic the state deems safe to drink: 10 micrograms per liter (ug/L).
The information reflects only well water tests conducted by the state-run Maine Health and Environmental Testing Laboratory — results from commercial water testing companies are unavailable — but it provides a useful snapshot. Arsenic and other drinking water contaminants often cluster in certain areas depending on the underlying geology.
You can see that clustering effect here. Thanks to my colleague Darren Fishell for creating this map.
Drinking water with high levels of arsenic can lead to skin damage, circulation problems, stomach pain, nausea, and tingling in the hands and feet. Over many years, it may raise the risk of developing cancer, including skin, bladder, and lung cancers, according to the U.S. Environmental Protection Agency. Arsenic exposure can also lead to low birth weight and affect brain development in young children.
Of course, the best way to know if your well water is contaminated is to have it tested.