More than one-third of the nation’s sewage systems have violated the law by unintentionally dumping human waste, chemicals and other hazardous materials into local waterways, according to a recent New York Times investigation.

This disturbing realization is the latest in a series of shocking discoveries uncovered by the Times’ Toxic Water series, which focuses on the worsening pollution in America’s waters.

So far, the series has looked at pollution from herbicides, industrial waste, agricultural runoff and power plants, all of which often make their way into the cups and glasses of Americans across the nation. 

The Times’ latest investigation looks at the sad state of the nation’s sewage system, which, due to a lack of upgrades, is frequently overwhelmed by common occurrences like heavy rainfall.

This is especially true in Brooklyn, N.Y., where an absence of trees and grass to soak up excess water means that heavy rainfalls can cause sewage overflows into nearby waterways. 

“It happens anytime you get a hard rainfall,” said Bob Connaughton, one of the engineers at Owls Head Water Pollution Control Plant where much of Brooklyn’s sewage is treated. “Sometimes all it takes is 20 minutes of rain, and you’ve got overflows across Brooklyn.”

Though one of the Clean Water Act’s purposes was to upgrade the nation’s sewage systems — some of which were built back in the 1800s — for the most part, these upgrades haven’t done enough to keep the sewage systems up to standard.

Worse yet, fewer than one in five sewage systems that have broken the law by dumping untreated sewage into the waterways have ever been fined.

Though no one knows exactly how many illnesses are caused by sewage spills, research suggests that as many as 20 million people a year get sick from drinking water that is contaminated with bacteria and other pathogens spread by untreated waste.

One study in a Milwaukee hospital found that the number of children suffering from diarrhea rose whenever local sewers overflowed.

In addition, some people have had to move out of their houses after sewage overflows ruined their property.

“After the storm, the sewage flowed down the street faster than we could move out of the way and filled my house with over a foot of muck,” said Laura Serrano, who says she contracted viral meningitis after her home in Bay Shore, N.Y., was damaged in 2005 by a sewer overflow. “I had to move out, and no one will buy my house because the sewage was absorbed into the walls,” Serrano said. 

Despite the fact that the EPA has been working to reduce or eliminate such overflows since the mid-'90s and that the stimulus bill passed set aside $6 billion to improve sewers and other water systems, the government still has a long way to go to fix a large problem.  

“The public has no clue how important these sewage plants are,” said Connaughton of the Brooklyn site. “We’re doing everything we can to clean as much sewage as possible, but sometimes, that isn’t enough.”