DENVER (KDVR) — The odds of being infected from drinking water are small in the U.S., though health authorities do document roughly two drinking water-related illness outbreaks every month on average.

Rates of illness or death related to drinking water are low in the U.S. In 10 years from 2011 to 2020, there has been one illness related to drinking water per every million people, according to U.S. Centers for Disease Control and Prevention surveillance data – about 352 people a year total.

There have been 1,149 outbreaks resulting in 586,145 illnesses, 1,663 hospitalizations and 288 deaths in the U.S. from 1971 to 2020. Legionella and giardia are the two largest sources of infection.

The number of drinking waterborne disease outbreaks and hospitalizations lessened since 1971, then grew since the mid-2000s.

The most illnesses in a single year came from the 1993 Milwaukee cryptosporidiosis outbreak. This was the largest waterborne outbreak in U.S. history, which resulted in over 400,000 illnesses.

The U.S. experience the most individual drinking water-related illness outbreaks in 1980, when there were 48 within the year.

There were low points in both 1996 and 2005, with seven outbreaks. Since 2005, the number of outbreaks has grown to 46 by 2019.

Hospitalizations grew in the same period, peaking in 2014 with the water crisis in Flint, Michigan. They remained at near-record levels through 2019.

Drinking waterborne disease outbreaks are concentrated most heavily in Mid-Atlantic, Great Lakes and Southeast states, with Colorado being the exception.

With 66 outbreaks since 1971, Colorado has the nation’s fourth-highest total behind Pennsylvania (147), Florida (112) and New York (77).

Nearly three-quarters of Colorado’s outbreaks, however, happened in 1983 or prior. In the last 10 years, there have been two – one in 2012 and one in 2016. Only in one of the 66 – a salmonella outbreak in 2008 – has any of Colorado’s outbreaks resulted in a death.