From the Middle Ages until the early 19th century, the cleanliness of towns and streets (in Europe and North America without distinction) has always been a problem. In the past, they were usually covered by excrement and dirt. Historians associate public health with cleanliness concerns. Cholera, typhoid fever, typhus, yellow fever, plague and several other infections were common in the past because of the poor hygienic conditions of the cities.

With the population increase in neo-industrial cities like New York during the 19th century, people’s hygienic conditions got worse. One big problem was the huge number of horses and other animals like pigs, sheep and cattle. Each one of those horses gave off 24 pounds of manure and several quarts of urine a day. Unfortunately, nobody cleaned the city every day.

The absence of flushing toilets and a sewage system were another problem. Rubbish, human waste, dead animals were abandoned along the streets. Rich people wore high heels to protect their clothes and walked down the city smelling strong perfumes to avoid the terrible stench.

The people in Paris, London and other European cities suffered from diseases caused by filth, like the black plague. One of the first sewer systems was built in Paris in the 19th century. At first, people did not want this new type of construction, as the installation of sanitary piping in the building was expensive.

Initially, the sewer system was normally open, until scientists studied the link between disease, contaminated water and squalor. From that point, modern sewage systems were built underground.

London began to clean its streets during the second half of the 19th century. In the USA, that practice began in 1849, with the invention of the first street sweeping machine.

Today, the problem is to preserve water quality, in line with environmental awareness, which has been growing since the Seventies of the past century.