A Brief History of Water Treatment and Sanitation

Even in early Greek writings dating back to 2000 BC, water treatment methods were recommended. People back then knew that heating water might purify it, and they were also educated in sand and gravel filtration, boiling, and straining. Because people could not yet distinguish between foul and clean water, turbidity, odor, and taste were the main driving force between the earliest water treatments. Turbidity refers to the "cloudiness" of water. Not much was known about microorganisms, or chemical contaminants.

The Ancient Egyptians first discovered the principle of coagulation, applying the chemical alum for suspended particle settlement. 1000 years later, Hippocrates invented the practice of sieving water, and obtained the first bag filter, which was called the 'Hippocratic sleeve'. The main purpose of the bag was to trap sediments that caused bad tastes or odors.

During the Middle (Dark) Ages, water supply was no longer as sophisticated as before because of a lack of scientific innovations and experiments. After the fall of the Roman Empire, enemy forces destroyed many aqueducts, and others were no longer applied. The future for water treatment was uncertain.

With the invention of the microscope by Van Leeuwenhoek in the 1670s, scientists were first able to watch tiny particles in water, and discovered the first water microorganisms. In the 1700s the first water filters for domestic application, made of wool, sponge and charcoal, were applied. In 1804 the first actual municipal water treatment plant designed by Robert Thom, was built in Scotland. The water treatment was based on slow sand filtration. Some three years later, the first water pipes were installed.

In 1854, it was discovered that a cholera epidemic spread through water. The outbreak seemed less severe in areas where sand filters were installed. British scientist John Snow found that the direct cause of the outbreak was water pump contamination by sewage water. He applied chlorine to purify the water, and this paved the way for water disinfection. Since the water in the pump had tasted and smelled normal, the conclusion was finally drawn that good taste and smell alone do not guarantee safe drinking water. This discovery led to governments starting to install municipal water filters (sand filters and chlorination), and hence the first government regulation of public water.

In the 1890s America started building large sand filters to protect public health. These turned out to be a success. Instead of slow sand filtration, rapid sand filtration was now applied. Meanwhile, such waterborne illnesses as cholera and typhoid became less and less common as water chlorination spread throughout the industrialized world.

But the victory obtained by the invention of chlorination did not last long. After some time the negative effects of this element were discovered. Vaporizing much faster than water, chlorine was linked to the aggravation and cause of respiratory disease. Water experts started looking for alternative water disinfectants.

In 1903 water softening was invented as a technique for water desalination. Cations were removed from water by exchanging them by sodium or other cations, in ion exchangers.

Eventually, starting 1914 drinking water standards were implemented for drinking water supplies in public traffic, based on coliform growth. It would take until the 1940s before drinking water standards applied to municipal drinking water. In 1972, the Clean Water Act was passed in the United States. In 1974 the Safe Drinking Water Act (SDWA) was formulated. The general principle in the developed world now was that every person had the right to safe drinking water.

Starting in 1970, public health concerns shifted from waterborne illnesses caused by disease-causing microorganisms, to anthropogenic water pollution such as pesticide residues and industrial sludge and organic chemicals. Regulation now focused on industrial waste and industrial water contamination, and water treatment plants were adapted. Techniques such as aeration, flocculation, and active carbon adsorption were applied. In the 1980s, membrane development for reverse osmosis was added to the list. Risk assessments were enabled after 1990.

Water treatment experimentation today mainly focuses on disinfection by-products. An example is trihalomethane (THM) formation from chlorine disinfection. These organics were linked to cancer. Lead also became a concern after it was discovered to corrode from water pipes. The high pH level of disinfected water enabled corrosion. Today, other materials have replaced many lead water pipes.