Total Chlorine in Water - Laboratory Analysis

The different types of chlorine

For swimming pools and spas, there are 3 types of chlorine you can test, each serving a purpose:

• Total chlorine - this is tested to measure the total amount of chlorine in the water, including free chlorine and combined chlorine. This lets you check whether the total chlorine concentration is within the recommended range to ensure effective disinfection.
•  Free chlorine - this is tested to measure the concentration of available chlorine in the water, which is the active chlorine capable of killing bacteria, viruses, and algae. It is important to test free chlorine regularly to ensure adequate water disinfection.
•  Combined chlorine - this is tested to measure the amount of chlorine that has bonded with contaminants in the water, forming inactive chlorinated compounds. A high combined chlorine level may indicate overchlorination or a lack of effective chlorination, which can lead to water quality issues such as skin and eye irritation.

In summary, testing total chlorine lets you monitor overall water disinfection, testing free chlorine ensures effective disinfection, while testing combined chlorine helps detect potential problems with overchlorination or underchlorination.

A closer look at total chlorine in water

Sources of total chlorine in water

Chlorine occurs in nature as free chlorine, combined chlorine, or both. 

Total chlorine = Free chlorine + Combined chlorine (chlorinated compounds formed by reaction with organic matter).

In water, chlorine is found in 3 forms whose balance varies with pH and temperature: the hypochlorite ion (ClO^-), hypochlorous acid (HClO), and the chloride ion (Cl^-). 

Chlorine is used as a disinfectant because it effectively eliminates a large proportion of the bacteria present in water, as well as algae, parasites, and viruses.

Standards for total chlorine in water*

Total chlorine is the chlorine that remains in water, whether it is free or has reacted. The WHO has established a guideline value of 5 mg/L, based on the absence of unpleasant odor or taste caused by chlorine.

Effects of total chlorine on the body

The main routes of exposure to chlorine are drinking water and food.

Total chlorine can damage the respiratory system and lungs and affect the skin, especially in moist areas of the human body (groin, armpits).

This paragraph is based in part on the WHO report " Guidelines for Drinking-water Quality ". 

*A guideline value is a reference value provided by the WHO.

How do you test your water's total chlorine level in a laboratory?

Here, we offer laboratory analysis of your water to determine its exact total chlorine level.

To do this, you must also order the basic laboratory analysis available here. This basic analysis includes a sampling kit and shipment of the kit to our independent partner laboratory.

Other methods for testing total chlorine in water

If you do not want the hassle of sending samples to a laboratory or think you may need to perform this test several times, you can test the free chlorine level in your water yourself!

The eXact iDip and eXact Micro 20 photometers let you test a wide range of substances and elements present in your water. Once you have the device, order the combined chlorine test for photometers.