How to Be Sure a Disinfectant Is Working?

It’s the middle of a cold, nasty winter and we all want to stay healthy. With both COVID-19 and the seasonal flu infecting building users, the Centers for Disease Control and Prevention has recommended disinfecting facilities with EPA-registered disinfectants, specifically those on the N-List. This is a list of products proven to deactivate the virus that causes COVID-19.

As facility manager, it is your job to ensure these products are used properly and effectively. What do you do if you suspect your disinfectant is not working to its full potential? Typically the problem is one of the following:

  • Using the wrong disinfectant
  • Diluting the disinfectant improperly
  • Applying the disinfectant improperly
  • Diminishing the effectiveness of the disinfectant (referred to as “quat binding”)

Let’s look now at how you can avoid these problems.


First up, you want to be sure your product is an EPA-registered disinfectant, or as referred to in the professional cleaning industry, an antimicrobial product. These have been tested and proven to be effective against specific germs and bacteria while also meeting certain environmental standards.

Disinfectants that have been registered by the EPA will have a registration number on the product label. The label will also list which pathogens the disinfectant should be used for.

Remember: Not all disinfectants are designed to kill all pathogens.

For example, while one disinfectant may prove effective at helping to stop the spread of MRSA, or kill salmonella, E. coli, or other bacteria and viruses found on surfaces, the same product may not be effective when used to kill norovirus or influenza. For COVID-19, only those products on the N-List are approved.

For this reason, administrators must always check the labels of the selected disinfectants. A janitorial distributor can be helpful in this endeavor. But what happens if there is some question as to what pathogens are present? Fortunately, “broad spectrum” disinfectants are designed to kill some of the most common pathogens in a facility.


As to the second issue — proper dilution — a wise and inexpensive investment that facility managers should consider is an auto-dilution system. This properly dilutes the cleaning solutions per the manufacturer’s recommendations. Proper dilution helps in two ways. First, it saves money by not using too much product, and second, it ensures the solution is as effective as promised.

Please note, more is not better when it comes to disinfectants and most cleaning solutions. The use of more chemicals means that more chemical residue will be left on the surface, which can actually attract soils and pathogens.


A common reason disinfectants fail to work effectively is that many cleaning professionals do not realize that disinfection is a two-step process:

  • Step 1: Clean the surface using an all-purpose cleaner or something similar. This removes any soils that might be present.
  • Step 2: Clean the same area using the disinfectant. With the soils gone, the disinfectant can get to work on any pathogens that remain.

Before applying the disinfectant, read the label and look for the “bacteria kill time” or “dwell time.” Dwell time is how long it takes for the disinfectant to be effective. With some disinfectants, this may be as little as three minutes. For others, it could be as many as 10 minutes.

During this dwell time, the disinfectant must remain wet. If it dries on the surface, it should be reapplied and the process repeated.



If you have never heard the term “quat binding” before, join the club. It is actually relatively new to the professional cleaning industry. Let’s break it down so we can understand it better:

  • “Quat” refers to quaternary ammonium chloride, an active ingredient found in most EPA-registered disinfectants.
  • “Quat binding” refers to the absorption of quaternary ammonium chloride into the cleaning cloth or, if mopping floors, into the mop head being used.

As the quats are absorbed, the disinfectant loses its effectiveness. Why does this happen? It’s science. Quats are positively charged, and many cleaning cloths and mop heads are manufactured with natural textiles such as cotton, which are negatively charged. This causes the quats to bind to the cotton.

In one study, the quat level of a disinfectant on a cleaning cloth was reduced by 50% after soaking for 10 minutes in the cleaning solution. After that, the pathogen-killing benefits of the disinfectant were significantly diminished.

There are several ways to prevent quat binding:

  • Apply the disinfectant directly to the surface to be cleaned and allow it ample time to work effectively.
  • Change the cleaning cloth or mop head (and the mop water) frequently.
  • Avoid using standard terry-cloth towels with disinfectants; microfiber is more effective at removing soils from surfaces and will not be as impacted by quat binding.

Another option is to look into different cleaning systems. Although they are not designed specifically to kill germs and bacteria, aqueous ozone cleaning systems and no-touch cleaning systems will not be impacted by quat binding because no textiles are used in the cleaning process. They can also address some of the other disinfecting challenges mentioned earlier.


Finally, managers and cleaning professionals should consider using ATP-monitoring systems. These devices are essentially an electronic petri dish. A surface is swabbed, and the swab is then put into the device, which looks like a television remote control. In about 15 seconds, the device indicates if ATP is present on a surface.

Although it does not indicate specifically what types of pathogens are present, a higher-than-usual ATP reading should always be viewed as a red flag, indicating that cleaning and disinfecting are necessary.

In these dark times, facility managers have a lot weighing on them. The effectiveness of disinfectants should not be one of them. Follow these steps to ensure your disinfection routine is delivering the results you and your customers expect.

Ron Segura, formerly Manager of Janitorial/Document Services for Walt Disney Pictures and Television, is a cleaning consultant working with corporate campuses, schools, and universities.

Contact us to discuss your cleaning needs by calling —732-901-5337—or by clicking on our logo below. We will take care of it.

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