Aircraft drinking water systems and watering points require sanitizing and this process takes valuable time.  In the hangar and on the ramp, time is money.  Aircraft in the hangar for maintenance (AOG) are not productively “flying the line”; thereby, not making money.

Administrative orders of consent, and FDA guidelines, require that all commercial aircraft drinking water systems be sanitized every 90 days.  Further, watering points, such as water trucks and water carts, are to be sanitized every 30 days.  New regulations are being considered and passed, that will establish requirements for periodic cleaning cycles, for all equipment coming in contact with drinking water for commercial aircraft use.

As the name implies, the AWOCS™ utilizes aqueous ozone, as a disinfectant; the purpose of which is to deactivate (oxidize) bacteria that may be growing inside the wetted areas (piping, valves, tanks, pressure regulators, hose; etc.) within an aircraft’s drinking water system or its watering points.  Uniquely, it will also penetrate the biofilms that harbor and foster the re-growth of organisms on these wetted areas.  Prior to our work with the FDA and the U.S. Environmental Protection Agency, the only approved method for sanitizing watering points was expensive and dangerous shock chlorination.  Shock chlorination procedures require predetermined concentrations of different chlorine compounds be introduced into aircraft drinking water systems and/or watering points for a “contact time” that is based on an average bioload; usually, 50ppm concentration for one hour. If the aircraft system or watering point being sanitized is seriously contaminated, one hour will not be long enough and, conversely, if it was relatively clean to begin with, the hour will be too long.  In both cases, time will be wasted. When using shock chlorination, it is also difficult to determine if the plane is sanitized at the end of the cleaning cycle.  To determine the success of failure, you must take a water sample and wait another 24 hours.  Only the AWOCS™ gives a real time indication of the health of the water system.  It runs just long enough (not too long and not too short) to assure the system is clean, matching bottled water quality levels, and then alerts the operator to flush, refill and move on.

Case Evaluation – AWOCS

Semler Industries spent six years developing the AWOCS unit and has been field tested at facilities across the US and Canada.

Real world experience, sanitizing aircraft, illustrates the AWOCS™ unique ability to alert the operator when the job is done.  The sanitizing time varies from several hours to 15 minutes.  Most of the aircrafts’ sanitizing time fluctuates because of the varying levels of contamination of each plane.

Benefits noted by customers have been:

  • Fully automated process
  • Ozone is automatically generated, mixed and dispensed in the correct concentrations as needed.
  • Fully portable
  • Instrumentation alerts operator when sanitizing has been accomplished.
  • Rugged and built to last.  Unit is at home on the ramp or in the hangar.
  • Dramatically reduces total cleaning time.
  • Operating cycle time last only as long as required to sanitize. Eliminates predetermined “soak time” that is indirectly calculated based on the concentration of chlorine based biocides.
  • Eliminates the need to order, store and mix aggressive and corrosive chlorine based chemicals.
  • No hazardous wastes to dispose of.
  • Little operator training required

Equipment Description

The AWOCS™ is designed on the basis of sound science and is user, hangar and ramp friendly.  While ozone is 3,000 times more powerful than comparable concentrations of chlorine, the ozone concentration used by the AWOCS™ is a mere 4ppm.  Subsequent independent tests have confirmed the science upon which our design is based and proved the system will provide both superior results and dramatic cost savings.  This system eliminates workers’ and aircraft exposure to dangerous corrosive chemicals and does away with expensive hazardous waste disposal.  No respirators, safety goggles, gloves or aprons are needed with the AWOCS™.

While there are a few competitors in this arena, many do not offer the same control of ozone or integrity of safety features to prevent gaseous ozone from escaping the system.  Beware the equipment that is “too simple”.  You may be compromising the health of you or your employees.

Regulating Agencies

After evaluating the AWOCS™, the FDA stated in its letter to us, “Your proposed use of ozone to disinfect drinking water and water for culinary purposes used on ICC’s is acceptable …”.  It went on further to point out, “Please keep in mind that the EPA regulates sanitizers used on the surfaces of articles (except packaging) or equipment used to contact food or water.”

Upon the EPA’s investigation of our system, it stated in its letter to us, “we believe ozone is an effective alternative disinfectant to chlorine”.  Then, referring to Water Service Guide 17, went on to say, “While the flushing and disinfection practice included in the document describes a chlorine solution as the chemical of disinfection, as we have stated above, ozone is an acceptable alternate to chlorine in the drinking water systems…”.  In both the referenced FDA and EPA letters, concerns expressed were overcome by the uniqueness of our system designs.  Simply introducing ozone into a drinking water system would not be acceptable to either agency unless other conditions were addressed.  Our system addresses all concerns.

If you are sanitizing with chemicals but would like to save time, the cost of labor, chemicals, safety equipment, and downtime, and eliminate the handling and disposal of hazardous corrosive chemicals, contact Semler Industries and ask for information about the AWOCS™.

Equipment Improvements

Since inception of the product design, Semler Industries has continued to make improvements including a touch-panel design for controls, improved positive displacement pump design, more robust fittings and other stepwise improvements to the cabinet and components.  These steps have been taken and will continue to evolve in order to assure the customer of the optimal reliability and performance.


Before looking anywhere else, evaluate the AWOCS for cost-savings in aircraft water line cleaning.


  1. AWOCS promotional piece, March 11, 2008.

Related Imagery

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