Some of the earliest known records of water treatment were found in Sanskrit writings dating as far back as 2,000 B.C., although some researchers suggest water treatment dates to 7,000 B.C. in the ancient city of Jericho. The most common methods of water treatment included the boiling of water over fire, heating of water under the sun, dipping heated iron into water, and filtration through gravel and sand.
Water treatment at that time was meant to reduce turbidity (particles of organic material that cloud the water) and foul odor, while water treatment systems mimicked natural processes of filtration.
Inscriptions on the ancient Egyptian tomb walls of Amenophis II and Ramses II depicted water filtration systems as early as 1,500 B.C. It is also known that Egyptians used alum to accelerate the coagulation of fine particles so they could more easily be filtered – a process still applied today in many water treatment facilities.
Around 500 B.C., Hippocrates developed a water filtration device known as the “Hippocrates Sleeve.” It consisted of folded cloth bags that were used to further filter boiled water. Once again, without knowledge of microbes, the purpose was to cleanse the water as much as possible by reducing turbidity and odor. This water was often used for medical treatments. Ancient Greeks and Romans used several different methods to produce cleaner drinking water, including the use of cisterns to let particles settle, boiling water over an open fire, and filtering water through charcoal or ash. The Romans are also famous for their extensive aqueduct construction to keep water flowing from mountain streams to nearby cities. The invention of the Archimedes screw, basically a screw encased in a pipe, was also used to pump water.
Public water treatment remained largely unchanged during the middle ages. Then, in 1671, Sir Francis Bacon experimented with desalination of water using sand filtration. He was not successful, but his work renewed interest in water treatment.
Also in the 17th century, the Italian physician Lucas Antonius Portius provided details of a sand filtration method using three pairs of sand filters. Water would enter the settling compartment of the system after it had been strained through a perforated plate.
It is important to note that in the 1670s, innovation in the field of glass lenses led to the invention of the microscope by Antonie van Leeuwenhoek. Along with Robert Hooke, they made observations of “tiny animals” that are today classified as protozoa and bacteria. Eventually this led to the scientific realization that there was more to our water than just turbidity and odor.
Between the 17th and 18th centuries, filtration became the preferred water treatment method for many communities, and more town officials were considering the possibility of providing clean drinking to their residents. In 1703, French scientist Phillipe De La Hire suggested that every household in Paris should have a rainwater cistern and a sand filter. His system included a covered and elevated cistern, which could prevent the growth of moss and freezing.
In 1804, over 100 years after La Hire’s advice, the town of Paisley in Scotland debuted the first municipal water treatment plant in the world. This treatment plant used gravel and sand filters developed by Robert Thom to treat water, and the treated water was distributed manually through horses and carts. . As sand filtration technology improved, it became more viable (but still an expensive investment) for use in towns wishing to provide residents with a source of filtered water. Sand filtration methods evolved to include a pretreatment process of coagulation and sedimentation of particles, since a reduction of sediment reduced the load on the filter. Charcoal filtration was added to improve taste and odor.
In the 19
century, a connection was made between recent cholera and typhoid outbreaks and water treatment. Significantly fewer cases of these diseases were reported in places where water had gone through a filtration and disinfection process using chlorine.
London passed the Metropolitan Water Act of 1852 to ensure that all water supplied to the city would be filtered. In America, it was not until 1972 when the Clean Water Act was passed. This legislation was designed to protect existing waterways from excessive pollution. At the time, the Great Lakes and the Chicago River, to mention a few, were severely polluted. In 1974, the Safe Drinking Water Act was passed. This law was designed to set standards for drinking water treatment, including acceptable maximum contamination levels of various pathogens and chemicals in water supply systems serving more than 25 people.
Clean tap water is now a reality for most people in developed countries. Having clean, treated water delivered to our communities and homes is a luxury that more than half of the world’s population enjoys. Per the World Health Organization, about 71% of the global population has access to a safely managed drinking water service. Unfortunately, that means over 2 billion people do not have access to clean water across the world (mostly in Africa and Asia).
Outbreaks due to contaminated water still happen in the developing world. In 1993, the city of Milwaukee experienced a major outbreak of
, a protozoan linked to runoff water possibly contaminated by cow manure. Over 400,000 suffered symptoms of gastrointestinal discomfort, and over 100 people died. The elderly and children are usually most at risk.
is a common bacterium that can also cause illness. It can colonize in water storages or pipes, and is responsible for over 2/3 of bacteria-related illnesses through public drinking water.
In 2014, a switch in water supply and improper treatment of water caused corroded lead pipes to leech a substantial amount of lead into the public water system in Flint, MI. Public water treatment in developed countries still carries a very low risk of contamination, as systems are not always perfect and require extensive monitoring to insure public safety. The greatest concern for treated water lies in providing it to the over 2 billion people without it.