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How do I Know if a Surface is Really Clean? [ATP Testing]

February 2nd, 2022 | 4 min. read

How do I Know if a Surface is Really Clean? [ATP Testing]

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“Out of sight, out of mind.”

Essentially what this phrase means is, ‘if we can't see it, don’t worry about it.’

Funnily enough, it actually applies to the cleaning industry.

Think of it this way.

Consider the kitchen table at your workplace or your office desk.

Because you can’t see the germs, bacteria, and debris with the naked eye, you forget that it’s there and in turn, believe that it’s clean.

Because you can’t visibly see how dirty the surface is, you don't even think about it.

We’ve all done this before and it’s okay. We get busy, that’s life.

But one important thing to remember is - although a surface may look clean, that doesn’t necessarily mean it’s actually clean.

So how can you be sure that the cleaning practices your current cleaner performs are efficient, doing the job they’re meant to, and keeping your employees safe?

Really. How clean is your site?


Enter ATP technology.

At In-Tec, we know ATP testing firsthand and have had plenty of our clients ask questions about this piece of technology. So, we’ve decided to answer your question by going through what ATP testing is, how it works, and why it’s beneficial.

What is ATP?

To really get into the definition of ATP, I have to get a bit sciency here so bear with me as I get into the nitty-gritty.

ATP (adenosine triphosphate) is a molecule present in all living cells and is responsible for transferring and storing energy. It can be found in all organic matter such as human, animal, and vegetable cells. You can even find ATP in insects, bacteria, yeast, mould, and bodily fluids (blood and saliva). It drives metabolic processes including muscle contraction, plant photosynthesis, cellular reproduction, fermentation in yeast, and respiration in fungi.

In other words, since ATP comes from so many different sources, its presence is all around us.

And as you’ll soon find out, ATP levels tell us whether a surface has been properly cleaned.

What does an ATP test measure?

Simply, ATP tests detect what is invisible to the naked eye.

It tests the bacteria load counts on surfaces and is a highly accepted form of testing for surface cleanliness.

An ATP test can’t detect viruses on surfaces, nor can it tell you what types of bacteria are present on a surface. However, it does reveal the presence of biological matter in a mere few seconds.

How does an ATP test work?

Now to the fun part – the piece of equipment that’s able to measure ATP levels.

At In-Tec, we conduct ATP tests via 3M’s LM1 Luminometer and test swabs.

The ATP testing process is as follows:

  1. Our cleaners take a swab of a surface that has been cleaned.
  2. The swab is then snapped and activated. This is where the ATP will react with an enzyme and eventually produce Relative Light Units (RLU).
  3. The swab is then placed in the Luminometer which measures the ATP level.
  4. In seconds, the device will give you an accurate reading of how much ATP is evident on the surface.

And that’s it! It’s a super easy process that verifies whether the cleaning procedures you have in place are working.

But how do I know whether the surface is clean or not? How do I know what is clean (pass) and what is not clean (fail)?

A great question.

The more organic matter detected, the higher the RLU reading will be.

Simply, the higher the test result, the higher the risk of infection – the cleaning is inadequate due to a high presence of ATP.

However, there is no right or wrong pass number that can apply to everyone. The amount of ATP on a surface after cleaning and the acceptable RLU reading depends on several different factors. Such factors include:

  • The material of the surface
  • How often the surface is touched
  • How often it is cleaned
  • What the surface is cleaned with

I know that that’s a basic answer and you were probably after specific numbers so below I have provided pass and fail rates that In-Tec follow for your reference. However remember, every environment is different so you should set these rates according to what you’re after.

Because as we know, what is deemed clean to one person may not be considered clean by another.

A reading of below 250 parts per million (ppm) is a good outcome, however, below 100 ppm is what should be aimed for. Thus, over 250 ppm is a fail. Whilst some will say that 0 ppm should be strived for, it’s not feasible to achieve this during every clean and on every surface.

What are the benefits of testing for ATP?

Peace of mind.

That is what ATP testing offers if you ever want to make sure that the cleaning procedures you have in place at your site are working and doing their job.

If your ATP levels are low, then great!

If your ATP levels are high, then at least you know something needs to be changed ASAP!

Remember, you want your cleaning company to be willing to conduct ATP tests if you’re unsure the surfaces in your workplace are being cleaned properly.

You also want your cleaning company to be using the appropriate cleaning products and solutions so that you don’t even have to worry whether your surface is clean or not and needs ATP testing to confirm.

If you’re wondering what type of solutions your cleaners should be using to get the most effective cleaning result, have a read of our article The 5 Best Eco-Friendly Cleaning Products of 2022.