Combined Chlorine - Laboratory Analysis

The different types of chlorine

For pools and spas, there are 3 types of chlorine you can test, each with its own purpose:

•  Total chlorine - this test measures the total amount of chlorine in the water, including free chlorine and combined chlorine. It lets you check whether the total chlorine concentration is within the recommended range for effective disinfection.
•  Free chlorine - this test measures 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 test measures 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 problems such as skin and eye irritation.

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

A closer look at combined chlorine

Combined chlorine, also known as combined residual chlorine, forms when chlorine reacts with organic substances and impurities in the water, such as sweat, urine, and organic debris. These reactions produce chlorinated compounds, such as chloramines and trihalomethanes, that are less effective at disinfecting water than free chlorine. Combined chlorine can cause an unpleasant odor and skin and eye irritation.

How can you have your water's combined chlorine level tested in a laboratory?

We offer laboratory analysis of your water to determine its exact combined chlorine level.

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

Other methods for testing combined chlorine in water

If you would prefer to avoid the hassle of sending samples to a laboratory, or if you expect to perform this test several times, you can test your water's combined chlorine level yourself!

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