Superstorm Sandy dumped 41 billion litres of raw and untreated sewage into US waterways from Washington to Connecticut, according to the science journalism group Climate Central.
That's enough human waste to cover New York's Central Park in more than 10 metres of sewage, or fill 17,000 Olympic-sized swimming pools, scientists said.
The group, which drew on data from the Environmental Protection Agency, state protection agencies and water treatment plants, said most of the outflow during the storm, which hit the eastern US in October last year, was caused by storm surges, which overwhelmed sewage treatment plants. Power shutdowns - and heavy rain in Washington - also played a part.
The scientists said the report exposed yet another risk factor to America's crumbling infrastructure, due to climate change.
New York authorities have been working for years to reinforce the city's subway system, which is vulnerable to flooding, and to shore up power stations along the coast. The scientists said that in the wake of Sandy, when storm surges raised water three metres above the high tide mark, it was time to look at waste-treatment plants.
"Our sewage infrastructure isn't built to withstand such surges and we are putting our property, safety and lives at risk if we don't plan for these challenges," said Dr Alyson Kenward from Climate Central.