The fury of a single monsoon cloudburst can precipitate enough water to overflow river banks.

ECONOMIST: From the archive

Newcastle City Council has warned the one to the north "is full of water, could overflow and cause more flooding if rain is heavy".

BBC: Newburn flooding: Do residents stay or go?

This report quoted Russian Investigative Committee spokesman Vladimir Markin as saying "there were no mass water releases or overflow over the dam" from the Neberdzhayevskoye Reservoir.

CNN: July 9, 2012 -- Updated 0150 GMT (0950 HKT)

These have traditionally played the role of water-catchment areas, absorbing any overflow from the river.

CNN: FIGHTING FLOODS

Unfortunately, these systems frequently overflow, and so untreated sewage and storm water runoff are expelled into surrounding water bodies.

FORBES: Spending Cuts Threaten U.S. Water Infrastructure

Above-freezing temperatures also led to overflow along the trail, a potentially dangerous situation where water has pushed up through the ice and refrozen, creating a weak top layer of ice that teams and mushers can break through.

NPR: 53-Year-Old Musher Becomes Oldest Iditarod Champ

When storms hit, these systems can overflow, sending untreated sewage into rivers, lakes, beaches, and drinking water supplies.

FORBES: Smart Communities will Build Green Infrastructure