Written by Kevin Liu | Edited by Josephine Chan
Photo by PS Photography
—begun in Part 1—
In addition to potential contaminants surviving chlorine treatment, the chlorine added to the water can also react with naturally occurring organic matter to create water disinfection byproducts (DBPs) [10]. These DBPs include chemicals like chloroform, which is known to cause cancer, and other chemicals whose effects on humans are not fully understood [10]. However, these are monitored and reported annually through the CCRs. For UC Irvine, the Irvine Ranch Water District is responsible for managing and reporting on the quality of the water supply. In their 2022 CCR, they detailed tolerable levels of chemicals and the results of testing for the aforementioned Cryptosporidium, various DBPs, and other elements present in our water [11]. If the presence of any chemicals or microorganisms is higher than the prescribed guidelines, the treatment facility must undergo a series of treatment procedures to ensure the water is safe to drink [11].
Effective as they are, chlorine and chloramines are not the only disinfectant treatment available. Another alternative is ozonation, which is the process of mixing ozone directly into the water. According to the Wastewater Technology Fact Sheet: Ozone Disinfection issued by the EPA in 1999, “ozonation is more effective than chlorine in destroying viruses and bacteria… it utilizes a short contact time… [and] there are no harmful residuals that need to be removed… because ozone decomposes rapidly” [12]. While widely accepted in Europe, ozonation is the least common method in the U.S. [12]. To use ozone as a disinfectant, ozone must be manufactured on-site because it quickly decomposes into oxygen [12]. In addition, a vast array of complex equipment is necessary to not only ensure proper disinfection, but to also keep workers safe, since ozone is highly toxic to humans [13]. Effectiveness aside, price is also a critical consideration. The Greenhouse Product News compared the costs to treat irrigation water based on data obtained from commercial greenhouses. In their Table 1, they compared the capital costs (i.e., the one-time cost of purchasing and installing the system) of different types of technology. An ozonation system’s capital cost was $170,420, while the most expensive chlorine system, which used chlorine dioxide, bore a capital cost of $8,136 [14]. While other considerations that play into the prices of the systems, such as the volume of water disinfected and the dosage of the disinfectant, chlorine remains the most widely used disinfectant in the U.S. Still, alternative technologies like ozonation aim to combat the presence of chlorine-resistant pathogens and toxic water DBPs.
At UCI and the U.S. as a whole, clean water is an almost-ubiquitous resource. Whenever we refill a water bottle, it is an act of trust, not only in the university to provide us with safe consumable water, but also in an infrastructure network that has been in the making since the early 20th century [2]. While each water district may have different procedures on water disinfection, they must meet the standards set by their state and the federal Environmental Protection Agency (EPA). Today, over 90 percent of US households get their water from a community water system—a testament to both infrastructural development and regulation [15].
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