Because drainage systems allow uncontrolled discharge of household and commercial waste, they may become contaminated with hazardous and even toxic materials. Normally in small quantities, they do not represent a short-term danger.

When large volumes are dumped into these networks, the danger is greater, as happened in the city of Guadalajara "Guadalajara (Mexico)"), Jalisco, Mexico on April 22, 1992, when a fuel spill in the sanitary drainage system caused several explosions along eight kilometers, in the Reforma sector, causing several deaths.

A regrettable example of the problem of insufficient urban drainage in a large city is that suffered by the city of New Orleans, in the United States, when Hurricane Katrina caused, at the end of August 2005, a catastrophic flood exacerbated by the difficulty in quickly draining the flooded parts and the failure of the Mississippi River levees that flooded the city at a higher level, even after the hurricane had passed.

The flood was so severe that it caused the death of some 29,000 people and caused enormous damage that is difficult to assess. The experience of said hurricane seems to recommend that pipes should have been built next to the river dikes that would collect the waters in openings of the dikes above a certain level, and lead them to the coast, where they would flow, thus limiting the possibilities of flooding.

Traces of drainage systems have been found in civilizations as ancient as those of the Indus Valley; However, these were superficial and not underground.

In the Roman Empire the system was efficient but pestilent: the Cloaca Maxima, prior to the imperial era, which still exists today, constitutes a notable example of Roman sanitary engineering. It was preferably used to drain swampy subsoil waters.

The first underground drainage network was built in Paris, France, in the 19th century. Many cities in Central Europe next to large rivers have had to build large hydraulic works for the drainage of sewage or sewage: such is the case of Vienna, where a part of the Danube was canalized to serve as a river port and an extensive underground drainage network was built that is partially shown in the film The Third Man.

Because drainage systems allow uncontrolled discharge of household and commercial waste, they may become contaminated with hazardous and even toxic materials. Normally in small quantities, they do not represent a short-term danger.

When large volumes are dumped into these networks, the danger is greater, as happened in the city of Guadalajara "Guadalajara (Mexico)"), Jalisco, Mexico on April 22, 1992, when a fuel spill in the sanitary drainage system caused several explosions along eight kilometers, in the Reforma sector, causing several deaths.

A regrettable example of the problem of insufficient urban drainage in a large city is that suffered by the city of New Orleans, in the United States, when Hurricane Katrina caused, at the end of August 2005, a catastrophic flood exacerbated by the difficulty in quickly draining the flooded parts and the failure of the Mississippi River levees that flooded the city at a higher level, even after the hurricane had passed.

The flood was so severe that it caused the death of some 29,000 people and caused enormous damage that is difficult to assess. The experience of said hurricane seems to recommend that pipes should have been built next to the river dikes that would collect the waters in openings of the dikes above a certain level, and lead them to the coast, where they would flow, thus limiting the possibilities of flooding.