When you drink a glass of tap water, fill a pan for cooking, or wash your dishes, you're probably not thinking about the chemicals that come out of your faucet. Don't let the idea of chemicals scare you though, tap water needs to be cleaned. Without disinfectant, your tap water would be full of pathogens and bacteria that could make you unwell - and could even be deadly.
We usually associate disinfectants such as chlorine with swimming baths, where it's used to kill off bacteria and other harmful microorganisms that could live in the pool. However, it's just as crucial when it comes to making sure that your tap water is safe enough to drink.
In this blog post, we'll explain how the process of disinfection works, what kinds of disinfectants can be used, and how you can be sure that your tap water is safe.
What Is Water Disinfection?
Let's start with the basics. Disinfection is the process of removing (or killing) dangerous bacteria while also preventing new microorganisms from growing. These bacteria are known as pathogenic organisms, a term that includes the bacteria themselves and associated bodies such as spores, viruses, and larvae.
Many bacteria are present in the original sources, such as lakes and wells, and must be removed before the water is safe for people to drink. However, water can also become contaminated by microorganisms found in the network of pipes that it travels through to reach our taps.
Disinfection is different from sterilization. This is when every microorganism is killed, regardless of whether they are actually harmful.
Why Is Disinfection Important?
Before disinfection became a common practice among tap water treatment companies, people could contract various waterborne diseases. Typhoid fever, cholera, dysentery, and even salmonella were all widespread around the world. Each is caused by pathogens present in the municipal water supply. In some countries, these diseases still occur when there aren't any clean supplies.
People have understood the link between dirty water and fatal diseases for thousands of years. As far back as the year 4000 BC, there are records that the Ancient Greeks used to filter their liquid through charcoal or expose it to sunlight to improve its purity. However, these methods are nowhere near as effective as the chemical disinfectants we use to treat our tap water today.
According to the Centers for Disease Control and Prevention, around 100 in every 100,000 Americans caught typhoid fever back in 1900. Thanks to modern methods of disinfection, this figure had fallen to 0.1 by 2006 — so it's no surprise that the process has been described as one of the 10 greatest public health achievements of the 20th century.
What Are The Most Common Disinfectants In The US?
Throughout the United States, the exact disinfectant in your tap water can vary. Although public systems are required to add a disinfectant to make their tap water safe, the exact disinfectant they choose to use is up to them. Many switch between disinfectants based on their availability. The main stipulation is that, whatever they pick, it must be present in all the water that travels through the pipe system.
Two of the most common disinfectants are chlorine (used by over 98% of US treatment plants) and chloramine. Chloramine is a compound that contains both chlorine and ammonia. We're all familiar with the distinctive smell of these chemicals from our public swimming pools, but you don't need to worry — you won't find the same variety in your tap water.
Drinking water usually contains monochloramine, whereas swimming pools contain dichloramine or trichloramine. These contain extra molecules of chloramine, which means it's stronger and not suitable for human consumption.
Other disinfectants that might be used include:
- Chlorine dioxide
- Bromine chloride
- Hydrogen peroxide
- Kwartair ammonium salts
When treatment companies use these disinfectants, the process is known as chemical disinfection. This is in contrast to physical disinfection, which refers to non-chemical processes such as boiling, UV exposure, or filtering to remove pathogens.
These physical disinfection methods are also incredibly useful in making sure our tap water is safe to drink. In fact, filtering is currently the most effective way to remove the dangerous parasites Cryptosporidium parvum and Giardia lamblia. These parasites are resistant to chlorine, so they cannot be removed via chemical disinfectant.
How Is Tap Water Disinfected?
The chemical disinfectant process is usually the final stage in ensuring our tap water is safe enough to drink. (Previous processes can include steps known as oxidation, coagulation, and settling). Professionals at a treatment plant add the chlorine, chloramine, or other chemical disinfectants to the water before entering the distribution system. This is the part of a supply network that transports the water from the centralized plant to residential and commercial properties.
When chlorine is added to tap water, the process is called chlorination. It's possible to add chlorine in the form of compressed gas, a liquid solution of sodium hypochlorite (NaOCl), or as calcium hypochlorite, which is a solid (Ca(OCl)2.
The disinfection works because chemicals such as chlorine can corrode the cell walls within a microorganism or pathogen. This prevents them from multiplying, meaning they will soon die out and leave the water pure.
Is Disinfected Tap Water Safe For Humans To Drink?
We all know the health risks that are associated with too much chlorine. Considering it was used as a weapon in the First World War, it's understandable to feel uneasy about the fact that it's present in our tap water! However, the doses used as a chemical disinfectant are far too low to cause any health concerns — and its benefits far outweigh the risk of a serious disease that comes from drinking untreated water.
The Centers for Disease Control and Prevention have stated that chlorine and chloramine levels up to 4 milligrams per liter are completely safe to drink. At this level, the chemicals are too dilute to have an adverse effect on your health. It might have a slight taste and smell, but as most people have drunk chlorinated / chloraminated tap water their entire life, many of us are unable to detect this.
Is Disinfected Tap Water Safe For Our Pets To Drink?
If you own pets, you might be unsure whether it's safe for your pets to drink disinfected tap water. For fish or other aquatic animals, including reptiles, you should always steer clear of giving them tap water. This is because they absorb the chemicals directly into their bloodstream, unlike humans and other mammals. As a result, it's not safe to give your reptile tap water to drink or use it to fill your fish's tank — unless the tank has a reliable filter inbuilt.
For other pets such as mammals and birds, the levels of chlorine or chloramine in your tap water are totally safe.
We hope this article has helped you understand the use of disinfectants in our tap water. Chemical disinfectants aren't just safe to drink — they are lifesaving additions that have saved countless lives since they were introduced to our water supplies in the early 1900s.