Types of Systems

In the ozone laundry industry, there are several approaches or methods used to dissolve ozone gas into water. Each of these methods is described below. Only one of these methods, the ‘Contact Tank’ method, addresses all of the requirements necessary to achieve reliable and measureable success. The other methods are only minimally effective at best.


One of the oldest and least effective is the ‘Bubbling’ or ‘Sparging’ method. This is where ozone is made and simply bubbled into the bottom of the washing machine with what amounts to an aerator stone like you would see at the bottom of a fish tank. This is the least effective method because the ozone is actually in contact with the water for the least amount of time and there is no pressure exerted upon the mixture of gas and water. In addition to that, bubbling ozone gas into a washing machine greatly increases the chances of worker exposure to ozone gas.

Direct Injection

Another method, called ‘Direct Injection’ is where ozone gas is injected directly into the cold water line right before the water empties into the washing machine. This method is only slightly more effective than the bubbling method. The ozone gas only has a fraction of a second to be in contact with the wash water before it empties into the washer. The improved effectiveness is related to the pressure inside of the pipe where the ozone gas and the water mixture are for this limited time. The pressure facilitates enhanced ‘mass transfer’ of the ozone gas into solution. This method also greatly increases the chances of worker exposure to ozone gas because of the gas being discharged directly into the washer.

Side-Arm Injection

A third method is called ‘Side-Arm Injection’. This method is truly the most complicated and expensive and only boots performance by a percentage point or two. A recirculation loop is installed on each washing machine where wash water is pulled from the washer continuously during a wash cycle and pumped through a filter on the floor at the back of the washer and returned to the wash wheel. More ozone gas is injected into the water line returning to the washer. The benefit is that ozone is continuously added to the wash water but the method of adding it is flawed and only a tiny portion of the ozone gas is actually dissolved in the water. The vast majority of ozone gas injected ends up being discharged into the washer where it increases the risk of worker exposure to ozone gas. There is a pump and a filter fitted to each washer that comes with all of the maintenance headaches associated with cleaning filters every day and keeping the pumps up and running in the cramped space behind your washers. There is an increased probability of leaks and the corrosion associated with those leaks for the washers and for the ozone equipment connected to those washers. There is also an additional cost for electricity to run the extra pumps and an increased safety hazard relating to the electrical pumps on the wet floor behind each of the washers.

Superior Method: Contact/reaction tank

At Water Energy, we have developed the ‘Contact Tank’ method to achieve superior results. This method is by far the very best way to achieve the desired level of dissolved ozone in your wash water. The Water Energy Ozone Laundry System uses a tall, stainless steel contact tank as part of a completely sealed system to facilitate superior mass transfer and provide superior safety margins. A bypass is connected to the cold water line coming into the laundry and water is directed through a contact tank where ozone is added and then the water is sent back to the cold water header and on to the washing machines just like it was before. Ozone bubbles are injected into the cold water line before the water goes into the contact tank. The ozone/water mixture enters the bottom of a tall, stainless steel tank where the bubbles of ozone are in contact with the cold water, under pressure, for 30 seconds or more. The water/ozone mixture travels up one side of the tank and back down the other before exiting the bottom of the tank and proceeding on to the washers. All ozone bubbles that are injected into the water rise toward the top of the tank. All bubbles that do not get dissolved into the water column remain at the top of the tank and are purged through a de-gassing valve. A Teflon tube takes all of this remaining ozone gas to the outside of the building where it is released harmlessly into the air. This process ensures that no bubbles of ozone gas ever enter the washing machines and it totally eliminates any risk of worker exposure to ozone gas! Water Energy, working with engineers at NASA over the last 30 years, developed this method of mass transfer in order to meet strict NASA guidelines set forth in the Space Shuttle Program. After years of research and millions of dollars spent on R&D, the Contact Tank method was certified the Superior Method of achieving efficient mass transfer of ozone gas into solution and maintaining safety margins for ozone exposure hazard. There are many more details as to why the Water Energy Contact Tank method is far superior to the other methods out there. We can discuss most of them with you in person if you really want to know why it just works better.

Other Methods we have heard of but don’t know how to classify:

Pressure cooker

One company out there literally pressurizes the washing machine and adds ozone gas directly to the pressurized washer. This is infinitely naïve. First of all, you should add the ozone independently of the washing machines. This will greatly reduce the risk of worker exposure to ozone gas and eliminate the possibility of corroding your expensive laundry equipment. Gaseous ozone is highly corrosive and liquid-phase ozone (ozone dissolved in water) is considered non-corrosive. Also, it is very expensive to close-up all the holes in a washer in order to pressurize it. Why waste your money on something that is ineffective! With this method, the risk of worker exposure to ozone gas is drastically higher because the washing machine contains pressurized ozone gas in close proximity to the laundry workers and the workers must continuously open the washers to add and remove linen. It just doesn’t make any sense to do it this way. These are but a few of the reasons to reject this approach.


Another company has equipment that supposedly makes several ‘forms’ of ozone that aren’t affected by heat and are deactivated when produced then after being transferred to the washers via tubing, are magically ‘reactivated’ where they can go about their job of cleaning and sanitizing. At Water Energy, we obey the physical laws and we know that there is only one type of ozone and once it is ‘deactivated’, it cannot be reactivated without going back through an ozone generator or a lightning storm. Don’t fall for any magic tricks. Rely on real equipment from real people. Rely on Water Energy Ozone Laundry Systems.