Ozone VS Chlorine Disinfection

“Water is life, and clean water means health.” – Audrey Hepburn

Safe, clean drinking water is essential for a healthy life, and a right for all of humankind to have access to. Unfortunately today, there are many people without access to one of our most basic human needs. Advances in technology have brought clean, drinkable water to billions of people around the world. Billions of people can go into a room in their home, turn on a tap and have access to seemingly crystal clear water on demand. Although the water in most of our homes may seem clean, and for the most part, maybe it is, there are almost always going to be some micro-biotic matter floating around and ending up in our bodies, causing an array of health issues.

Two common ways we have combated these unseeable invaders in our water are with chlorine and ozone. Chlorine is a chemical element that is added to water in small quantities to kill algae and other impurities that could cause illness. Ozone is a molecule comprised of three oxygen atoms stuck together, commonly found blocking the UV rays from the sun in our stratosphere, or at ground level after a lightning storm. Ozone is also a very effective disinfectant, able to kill almost all bacteria, viruses, fungi or parasites, as well as break down hazardous gases like hydrogen sulfide.


Both Chlorine and Ozone are effective at disinfecting water and have been used to protect municipal water supplies for decades. It has been found that ozone is much faster at disinfecting water and does so more effectively than when compared to chlorine. Ozone disinfects water by oxidizing germs, bacteria, viruses, parasites and metals immediately on contact. After being used, ozone breaks down and returns to a more stable element, oxygen, and leaves no trace of smell, taste or chemical residue. Chlorine on the other hand, once added to water, requires some time to completely dissolve and rid the water of harmful material. However, not all harmful matter can be removed the water with chlorine, such as some metals, gases and chlorine resistant parasites. Chlorine also leaves a distinct chemical smell, taste and residue which over time can be especially annoying and dangerous.


Water disinfected with ozone and or chlorine has multiple applications, the main one being cleaning municipal water supplies in urban areas. While chlorine is most often noticed and easily recognized because of it’s distinct smell and taste, ozone purified water has been used to disinfect municipal water beginning as early as 1906 in Nice, France. Since then, ozone has been becoming a more popular choice for disinfecting water than its counterparts.

Now, Ozone is not only used to disinfect large scale municipal water, but can also be utilized in smaller scale applications thanks to the advancements in technology since the early 1900s. Ozone generating water systems can be easily installed into a home and be used to sterilize water used for doing the laundry, taking a shower, washing dishes, cleaning surfaces, and of course, drinking.


The cost of using chlorine versus the cost of choosing ozone as a disinfectant differ greatly. Chlorine is relatively much more inexpensive initially when compared to the set up of an ozone generating device. Ozone-generating water filters can range in price from a couple of hundred dollars to thousands. That being said, the initial cost to set up an ozone generator is only a one time cost, and will continue to produce a higher quality of water for years after its initial installation. Chlorine is commonly used to disinfect water because it is so cheap, usually costing only cents per liter. When using chlorine to disinfect water, you must constantly replace the chemicals after being used, meaning even though it is so cheap, it is a reoccurring cost and will need to be resupplied indefinitely.


Chlorine for the purpose of disinfecting water is commonly purchased in a solid or liquid state. This makes the transportation and storage of chlorine relatively simple. Chlorine is also a stable element meaning it can be stored for a very long time if it is not being used. Ozone on the other hand is an unstable compound and has a half-life, which means over time, usually in a matter of minutes, ozone molecules will break down and turn back into oxygen. This makes the storage of ozone extremely difficult and impractical. If choosing to use ozone as a disinfectant, ozone must be produced or generated on demand as soon as it is needed.


Ozone and chlorine are both relatively safe ways to disinfect water. Very low, trace amounts of chlorine or ozone in water are completely harmless and can be consumed without worry. However, both have to be used with caution and must be considered thoroughly before being used.

Chlorine in a concentrated state, before being added to water, is extremely poisonous and can cause serious harm or even death if consumed. Once added to water, chlorine is broken down and dissolved, making it less harmful, but not completely. There have been trace amounts of chloroforms and halomethanes found in water disinfected with chlorine, both of which are known cancer causing carcinogens. There are also some waterborne parasites found to be resistant to chlorine, meaning they can also be easily consumed with infected water, causing serious illness.

Ozone is much more effective at killing nearly all viruses, bacteria and parasites, even those resistant to chlorine. Ozone is completely harmless when used in water as it will eventually break down into oxygen, leaving no chemical residue. Ozone as a gas is also completely harmless at low concentrations, although if exposed to very high concentrations of ozone gas, it can cause headaches and some discomfort. 

While chlorine and ozone are used around the world for their disinfection properties, in terms of which one is right for you in your home is completely dependant on your needs and means. There are many things to consider before choosing to use chlorine or ozone as a disinfectant in your home.

Even though the initial cost of using ozone as a disinfectant is higher relative to the cost of using chlorine, it is definitely something to be seriously considered. In the long run, the health benefits and quality of water purified by ozone justify the cost of having an ozone-generating water filter installed in a home. Pure, clean, safe, tasteless drinking water should not be seen as a luxury, but as a necessity for all.