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What is the difference between free and bound chlorine?

What is the difference between free and bound chlorine?

We start by indicating the following three concepts within the chlorine spectrum:

  • Total chlorine value
  • Free/active chlorine value
  • Bound chlorine

Below, the concepts are explained using examples:

The total chlorine value
This value shows the total amount of chlorine in your water, but this says nothing about its performance.

This is because the total chlorine value consists of active/free chlorine and bound chlorine.

Free/active chlorine value
This value indicates how much active chlorine your water contains. This level determines disinfection and is between 0.5 and 2.5 ppm.

Bound chlorine
This is chlorine that is no longer active. It has done its disinfecting work and then actually counteracts disinfection. This has a strong odour and can irritate eyes and mucous membranes.


It is therefore also the case that the lower the bound chlorine value, the better. In addition, the bound chlorine value should never exceed the free chlorine value! This is because then the disinfection process will not work.

The following formulas can be used when calculating chlorine values:

Free/active chlorine + Bound chlorine = Total chlorine
Total chlorine - Free/Active chlorine = The bound chlorine content

We are happy to help you accurately and reliably measure and monitor the desired chlorine content with one of our measuring instruments. View our range of chlorine meters here.