Buzz
A recent study discovered that tap water contaminants might be responsible for 100,000 cancer cases annually in the US. While these figures could be accurate (though it’s hard to verify), it doesn’t necessarily mean you should be overly concerned about your tap water.
These findings fall “within a similar range of cumulative cancer risk as air pollution... but that doesn’t mean you should stop going outside or cease breathing the air,” explained Daniel McCurry, an environmental engineering researcher specializing in drinking water systems who was not part of the study.
The researchers, in collaboration with the Environmental Working Group (whom I, personally, have long been quite skeptical of), released a report detailing the estimated cancer risks from various contaminants found in tap water. For instance, 0.004 micrograms of arsenic per liter is thought to pose a one-in-a-million risk of developing cancer. (These estimates are mainly derived from animal studies, and there’s no way to accurately determine how many actual human cancers could be linked to tap water.)
The authors estimate that, based on the US population, around 45,000 cancer cases occur annually due to contaminants. Other substances, including byproducts from the chemicals used in water disinfection, pose lesser risks, adding up to approximately 100,000 lifetime cancer cases that may be linked to tap water exposure.
What should you do if you're concerned about the quality of your tap water?
Sadly, there are few options available. Tap water is inexpensive and generally safe. Experts, like McCurry, who specialize in water system design and research, can use studies like this one to assess population-level risks, but this doesn’t provide direct, practical advice for individuals like us.
The primary carcinogen identified in this study is arsenic, which isn't a result of water treatment processes. Instead, it's naturally occurring in water, depending on the local geology. Switching to well water or bottled spring water wouldn't necessarily eliminate exposure to arsenic.
If you opt for bottled water, be aware that microplastics and chemicals from the plastic bottles may leach into the water. Furthermore, most bottled water is essentially just tap water in a bottle.
One potential solution is to use a filter for your tap water. While not all filters are equally effective, a 2017 study discovered that the ZeroWater pitcher outperformed other pitchers in removing arsenic. Many filters, particularly those with activated carbon, can also eliminate disinfection byproducts identified in the study.
Whether you use a filter or not, the risk is very low: about one in 10,000, assuming the numbers hold up (though there is significant uncertainty in these figures). McCurry personally drinks unfiltered tap water, but he knows others who prefer filtering theirs. So, if you choose to filter, go ahead, but don’t stress over it.
