Thread by @AlexPetrovnia

Happy #WorldWaterDay! The clean water that simply flows into your homes doesn't end up there by accident. Sanitation has revolutionized your life whether you've ever paid any attention to it or not. How did that come about? Read on to learn more. 🧵

So modern sanitation largely occurred in the western world due to one thing; cholera. For those who don't know, cholera is a waterborne illness that travels through a fecal-oral route. You can read more about cholera from my prior thread on it here:

https://twitter.com/AlexPetrovnia/status/1485451794251759620?t=vBbYMGY3qL-j-82Ys6mlCw&s=19

Cholera is incredibly deadly and has caused massive death and destruction in its 200 year history, spanning seven total epidemics. The first epidemic began in 1817, and the final epidemic is still ongoing today. So how have we fought back against this scourge on humanity?

Sanitation. The medical technology that has saved countless lives and largely goes unnoticed by those in the industrialized world. It is thanks to sanitation that cholera can be treated as a mere curiosity by many, despite being a grim reality for many others.

But sanitation measures don't just protect us from cholera. They protect against a whole host of waterborne diseases, including typhoid, hepatitis A, giardia, dysentery, E. coli, salmonella, and other diarrheal and parasitic infections.

The history of sanitation is far more ancient than many people realize. While the vast majority of people throughout history took their water from open water sources without intervention, several notable cities pioneered incredibly advanced ancient sanitation systems.

The very first rudimentary sanitation system that we have evidence of is at an archeological site known as Skara Brae. It dates to about 3000 BC and featured latrines and a rudimentary freshwater delivery system within houses.

Many ancient human societies also utilized wastewater as a resource for fertilization of agricultural fields, such as the Minoans, Mesopotamians and the Indus Valley civilizations.

In Peru, the Nazca civilization made interconnected wells and massive networks of channels that assisted them in obtaining and maintaining water supplies in the deserts they called home.

The Mesopotamians are the first civilization we know of to have utilized clay sewer pipes to collect and reroute wastewater. This was then used for irrigation of farmlands. The Hittites took this a step further and invented clay pipes with interlocking, repeated segments.

Societies in a ancient Persia, China and Egypt also created early sanitation systems. The fact that sanitation systems were invented repeatedly in so many societies speaks directly to their importance to human societies.

The Indus Valley Civilization utilized large public baths and public toilets. There is even evidence in certain settlements of separate rooms designated for bathing, with drains that flowed to the cities' central sewer.

The Minoans were the first civilization that we know of to use underground sewer piping, rather than above ground channels. They had incredible sanitary advancements incl stormwater runoff drainage, various sizing of piping and periodically flushing their system with clean water.

The Minoans, the ancient Greeks and the Mayans all incorporated systems that allowed for pressurized water for showers. Heron, a Greek inventor, even invented sprinkler systems for fire prevention.

Famously, the Romans had an incredibly sophisticated sewer and drinking water system, with aquaducts spanning miles and underground sewage management that deposited sewage from public toilets and baths into rivers. They also had indoor plumbing that terminated in individual homes

But sanitation systems in the modern western world largely stem from the threat cholera posed to major cities. After the discoveries of Dr. John Snow we're accepted as fact, the science of water sanitation became the path forward for many cities, with often extreme renovations.

In Europe between the fall of the Roman Empire and modern sanitation, the most common utilized method for sanitation in cities was the cesspit; pits in which waste is dumped to slowly seep into the ground. Where groundwater wells are utilized, this is a major problem.

The underground sewer systems built in major cities often required that entire cities be lifted up. The city of Chicago, for instance, was entirely raised by up to 15 feet to allow for a centralized sewer system and reversed the flow of an entire river to carry away waste.

This led to Chicago having one of the lowest mortality rates of any industrialized city in the late 1800s. While they were an early acceptor of this new technology, they were far from the only one.

Cities all over the world began taking on massive infrastructure projects to protect their citizens from infectious disease. A new era of prosperity, health and wellness emerged. Infant mortality plummeted. Plagues no longer brought cities to their knees.

But unfortunately, the grand era of sanitation investment has not been well maintained. Many major cities in Europe and North America have plumbing and sewage systems that have not been updated in decades or even over a century. Many of these vital systems are crumbling.

Many major cities sewage systems operate on the combined flow model. Put short, this means that when large influxes of stormwater are added to the system, the overflow is directed through the sewer system. If the system becomes overwhelmed, mixed stormwater and sewage can back up

The strain of age on these systems, combined with increasing flood risks in many regions due to climate change, mean that sanitation systems are long overdue for an update in many municipalities. If we aren't careful, the age of waterborne infectious disease may return worldwide.

Crucially, we are at another crux in public health. New, deadly airborne diseases could inspire us to invest in massive infrastructure to promote clean air, particularly indoors. This could be revolutionary for not only airborne diseases but for air pollution's long-term effects.

The world has rallied before against many infectious diseases and beat them back due to centralized investments in infrastructure. We stand at a critical turning point again, not only to reinvest in our sanitation systems as climate change bears down, but to invest in air quality

As we discuss sanitation, it is critical to discuss regions of the world where basic sanitation is still not available. If you enjoyed this thread, please consider supporting efforts to expand clean water access for all here:
water.org