Once ozonated water is made, it’s important to know that the effects can be short-lived. Temperature is the main variable if you want to extend the shelf life of the water. For instance, keeping the temperature of the water slightly chilled (around 58°F) can make a big difference compared to room temperature (around 77°F). At room temperature the half-life of ozone in water is about 15 minutes, while the half life of ozone in chilled water is closer to 30 minutes.The warmer the water, the shorter the half-life.

What is half-life?

The half-life is the time it takes for the ozone to be reduced to half its initial strength. The half-life countdown begins once you stop bubbling ozone into the water.

To illustrate this point better I’ve included two charts below that start with the same concentration of ozone in the water. Please refer to this article for more information on how to get a similar strength with your equipment. The first chart shows how much ozone remains in 58°F water over different lengths of time. The second shows the same for 77°F.

As you can see, ozone lasts much longer in chilled water, with some amount remaining up to four hours.

The next chart, derived from information from the Ozone Solutions website, shows the half-life amount based on different temperatures. For example, at 86°F, the amount of ozone in the water will reduce to half in 12 minutes. At 68°F, ozone will decrease to half in 20 minutes.

Half-Life of Ozone
Dissolved in water (7 pH)

If you are planning on drinking the ozone water shortly after making it, don’t like drinking cold water, or if you have sensitive teeth and are using it for dental irrigation, you won’t be missing out on any added benefits of colder ozone water by drinking it immediately (within 5-10 minutes) at room temperature. It’s just going to last longer in a colder batch.

Even if you store the water in the refrigerator, keep in mind that, at 58°F, the ozone in the water decreased to ¼ after an hour and ⅛ after ninety minutes. If you want more ozone than that you might want to ozonate it again at that point.

What if it still smells of ozone?

One deceptive thing about the half-life of ozone in water is that you can leave ozonated water in a container in the refrigerator for several hours, or even days, and when you go back and smell it you can still smell ozone. This might lead you to believe that there’s still a lot of ozone in the water, but it’s actually illustrating our ability to detect miniscule amounts of ozone. The reason you are still smelling it is because it doesn’t take very much ozone for the nose to detect it (threshold amount to detect ozone is .005 ppm [source]). However, if you had the ability to test the ozone in solution, you’d be better able to determine how little is actually left.

We hope this helped you decide the right way to make ozonated water for your needs. At room temperature, drink or use it within 5-10 minutes. If chilled it will last much longer, but may still need to be ozonated again later if it no longer contains the amount of ozone you desire.