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Water and sanitation

29 April 2016

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Water is a prerequisite for life and for the functioning of our complex societies. Last week's post illustrated how engineers and scientists progressed in securing water supply to cities. The supply and abundance of water was of course the initial concern, but as urbanisation increased, cities began to suffer through bad sanitation and hygiene.

The greatest killers of all

It is suspected that waterborne diseases were among the main causes of death in Ancient Rome and Greece. Roman authors also speculated about the danger of lead being used in their piping.

During those times, malaria and schistosomiasis were considerable waterborne killers. They spread easily across the Mediterranean due to maritime trade.

Bright minds of the past had been doing their best to stop all this. Experiments to improve the smell or taste of water were conducted thousands of years ago. Around 350BC, Hippocrates advised citizens to boil their water but his research focused only on parameters you could smell, taste, touch or see with the naked eye.

It wasn't until the 19th century that causes of waterborne diseases like cholera, dysentery, typhus, and hepatitis A were discovered and fatal epidemics were attributed to poor sanitation and water quality. These discoveries triggered drastic improvements in water infrastructure, notably including Joseph Bazalgette's mid-19th century project on Victorian London's sewer system.

It became clear that turbidity is not only an aesthetical problem but also a health hazard and so was tackled - on the visible level - by slow sand filtration. A notable milestone in treating water took place in Glasgow in 1808, where Richard Gillespie devised a filter system using a layer of sand and gravel. In 1847, polluting drinking water was made a criminal offence in the UK.

Filtering and disinfecting

The introduction of filtration saw tremendous results across global water networks: Lawrence, a city in Massachusetts, witnessed a 5-year decline of 79% in the death rate from typhoid fever and a general reduction of death rate by 10%! (Drinking Water and Health, published by the National Research Council, 1977).

A major breakthrough in securing water safety was the first use of disinfectants: ozone was first applied on industrial scale in Oudshoorn, Netherlands in 1896 and later in Nice, France in 1906. Maidstone, in Kent, was the first to have the entire municipal supply treated with chlorine.

The example of Wheeling, West Virginia, demonstrates the power of chlorination. While the incidence of typhoid fever in town had been around 155-200 per 100 000 inhabitants during 1917-1918, the application of chlorination in 1918 resulted in only 7 cases recorded in the first quartile of 1919. After technical revisions, only 11 additional cases were reported by the end of the year (Drinking Water and Health, 1977).

Technologies perfected but not disseminated everywhere

Water and wastewater treatment technologies have been successfully perfected and disseminated in developed countries since the early 20th century. It remains an alarming fact, however, that in developing countries, 80% of diseases are still caused by lack of basic sanitation and safe water. Around 1.5 million children die every year as a consequence. Globally, 6.3% of all deaths could be prevented with improved sanitation and access to drinking water.

In 1977, an important quest was set at the United Nations Water Conference:

"...all people, whatever their stage of development and their social and economic conditions, have the right to have access to drinking water in quantities and of a quality equal to their basic needs."

UN's new Sustainable Development Goals are still ambitious about water. Goal 6 states that by 2030, humanity has to "achieve universal and equitable access to safe and affordable drinking water for all."

Let's keep our fingers crossed and contribute to reaching all the SDGs. Hopefully, we will have a future that sees water as a historical killer only.