There are more than 326 million trillion gallons of water on our planet. Our bodies are made up of around 60% water. Even the air that we breathe has water vapors in it. Water is everywhere, but the water we can use is limited. According to the National Groundwater Association, the Earth is made up of about 71% water. Out of that, 99.7% is trapped in oceans, icecaps, soil, and the atmosphere. That leaves us with around 0.3% of the Earth’s water to use and drink. The same water that all living and nonliving things have used again and again since water has been on the planet.
Every morning I go downstairs to the kitchen and pour myself a glass of cold water from a water filter. Without a second thought, I drink the water because I consider this water to be safe. After all, the porous, activated carbon filters absorb various chemicals, including chlorine, lead, and mercury, which ‘purifies’ the water. Furthermore, I don’t have to worry about what could be in the water, because I know that the water is thoroughly cleaned before it enters the house. But how is it cleaned? Where does this water come from and what does it go through in order to splash into my kitchen sink?
Let’s start with a broader concept: rivers. Most major cities can be found along rivers: Paris along the Seine River, London along the River Thames, Seoul along the Han River, and New York along the Hudson River. This is no surprise, as communities need fresh, drinking water as an essential part of building a city. Pittsburgh is no different. In fact, in Pittsburgh, two rivers, the Monongahela and the Allegheny form a third, the Ohio, which on its passage through Pennsylvania, West Virginia, Ohio, Kentucky, Indiana, and Illinois, is the primary water source for over five million people. Within the city, the Allegheny River provides us, the people of Pittsburgh, with fresh water that we use on a daily basis.
If my water comes from the Allegheny River, what’s the difference between drinking tap water and river water? That’s where the Pittsburgh Water and Sewer Authority, or the PWSA, enters the picture. PWSA is the organization in charge of providing quality water throughout the city of Pittsburgh. The organization’s drinking water system “contains approximately 965 miles of water lines, five reservoirs, and 11 tanks with a water storage capacity of 455 million gallons” (pgh2o.com). And their process for making clean water looks like this. First, the collected river water is coagulated using ferric chloride, potassium permanganate, carbon, and catatonic polymer, which react to the polluting particles in the water, causing them to stick and clump together. The water is then taken through the filtration process, where it flows through pulverized anthracite coal and sand to remove any of the remaining particles. Afterwards, the water is disinfected with sodium hypochlorite, a type of chlorine compound that is used to remove microbial particles. Lastly, once the water has been completely purified, fluoride, the processed form of a naturally occurring mineral, is added back into the water as recommended by the Center for Disease Control to prevent tooth decay.
As complex as this purification process is, it isn’t perfect. The quality of the water that we receive is affected by what we put into it and there are countless compounds that cannot be completely filtered out by the processes used in water treatment plants. For example, trace amounts of dioxane, a likely human carcinogen from plastic manufacturing runoff, can be found in Pittsburgh’s own water system. Moreover, as of 2019, the PWSA has introduced orthophosphate in order to reduce lead levels, originating from the city’s ancient water pipes, in our tap water. In the end, all the water treatment plants can do is clean the water, test for contaminants, and research new ways to produce and deliver as clean a product as possible. The rest is up to us, the community. It’s up to us to be cautious of how we treat water by watching what we flush, preventing littering, or even reducing plastic use to reduce both microplastics and plastic production.
Water treatment is a growing process; new methods to remove previously unfilterable chemicals are constantly being discovered. With this in mind, think about your relationship with water. How do you treat it? What kind of objects do you flush down the toilet? What are your direct and indirect interactions with our water system? All of our actions matter. Because what we put into the river, will eventually come back to us.
Daniel Noh is an intern for the Center for Anthropocene Studies, Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.