How to Test for Chlorine in Water: 2021 Ultimate Guide

How to Test for Chlorine in Water 2021 Ultimate Guide

We’re fortunate to live in an era where pure water is readily available in most countries. However, it is still crucial to identify if you and your family members have access to the most purified form of water.

If you get your water from a city source, you probably assume that you’re obtaining quality potable water. After all, your water gets treated by your local authority before it reaches your home. But what if that water treatment is actually a cause of specific contamination?

Chlorination of water might protect us from exposure to harmful drinking water contaminants, but chlorine itself is a chemical with harmful health effects.

In this guide, I’ll be sharing everything you should know about chlorine in drinking water – why it’s added, how to test for chlorine, how to remove it, and more.

🧐 Why is Chlorine Added to Drinking Water?

Because it has several benefits, chlorine is added in small amounts as a disinfectant. It oxidizes natural substances and is an excellent disinfecting agent.

Over the past few decades, the transition to chlorination of water has been linked to an immense shift in public health. Treating water with chlorine-based disinfectants kills pathogens like bacteria, viruses and protozoa, which can cause disease and make us sick if we consume them.

Drinking water being poured into glass

Chlorinated water contains only a low free chlorine level, and is considered safe for consumption. However, many people would prefer not to drink any amount of chlorine, because it tastes unpleasant, and because it is a contaminant with known health effects.

You might wonder why chlorine is added to our water if it is potentially harmful to health. Why not use another means of killing microorganisms?

The answer is that chlorine is relatively cheap and readily available. Other means of disinfection, like reverse osmosis and UV purification, are very expensive in large-scale applications. Public water systems can keep their costs down by using total chlorine to disinfect water, because of just how affordable and available it is.

❔ Should I Test My Water for Chlorine?

If you get your water from a municipal supplier, I recommend testing for chlorine in drinking water.

All municipal water suppliers use either chlorine or chloramine to disinfect public drinking water. For your family’s safety, it is best to identify toxic disinfection byproducts in drinking water and have your chlorine level checked. 

📌 How to Test Water for Chlorine

Test Kits

There are several test kits you can use for chlorine testing, depending on the type of chlorine you’re testing for (free chlorine, total chlorine, residual chlorine, etc. ), and the source of water you want to test.

Pool Test Kits

In this method, a liquid chemical referred to as Orthotolidine is used. It changes the color to yellow, indicating the presence of total chlorine.

To use a pool test kit, just fill a tub with water, add 2-3 drops of solution and look for the color change. Keep in mind that this technique doesn’t measure free chlorine, but only the presence of total chlorine.

Color Test Kits

In this technique, a tablet chemical, referred to as DPD, is used. It causes the color to change to pink, indicating the presence of chlorine.

Using color test kits is a simpler and less expensive approach in comparison to digital meters. If used properly, this test gives accurate results.

Chlorine Test Strips

Chlorine test strips are a common option for testing for free chlorine or total chlorine in your home’s drinking water source.

To use chlorine test strips, take a strip from your test kit and dip it into a sample of water. Some test strips may need to be held under running water, so be sure to read the instructions carefully.

Man holding Chlorine Test Strips

After a couple of minutes, remove your test strip from the water. Compare the test strip to a color chart – which should be included in your test kit – to determine how much chlorine is present in your water.

Using test strips is one of the simplest means of chlorine testing if you want an idea of how much chlorine your water contains.

Digital Colorimeters

One of the more accurate chlorine testing methods is a digital colorimeter.

Digital colorimeters use two different methods. In the first, a DPD tablet is added to the sample water. This causes the change of color to pin, indicating the presence of chlorine.

hach dr300 digital colorimeter

The second method is the insertion of a vial into the meter. This reads the intensity of color change by emitting wavelengths. Digital colorimeters give fast results and highly accurate readings.

Certified Laboratory Testing

If test strips and other at-home testing methods don’t produce the precise results you’re looking for, I recommend using a certified laboratory water test.

Certified laboratory testing can provide information on your water’s exact free chlorine or total chlorine levels. In this kind of water test, you’ll send off a water sample to the laboratory, which will then test your water and provide you with the results several days later.

My recommended certified lab is for chlorine testing is Tap Score by SimpleLab.

The Essential City Water Test tests for both chlorine and chloramine, which is handy if your state uses a combination of both chemicals, or just chloramine, to disinfect your water.

This test also screens for common city water contaminants, like lead, fluoride, hardness, copper, and nitrate. If you’re considering a water treatment system that can remove a range of contaminants, knowing exactly what your water contains is a good place to start.

🤔 Should I Remove Chlorine from My Drinking Water?

As I’ve mentioned already in this guide, low levels of free chlorine are not considered harmful to health. However, because there are risks associated with this contaminant in high levels, you may want to remove it from your water entirely.

The Environmental Protection Agency (EPA) deems a low amount of chlorine of up to 4 milligrams per liter (mg/L) or 4 parts per million (ppm) safe for consumption. Harmful health effects are “unlikely to occur” when chlorine levels are this low – but you may still prefer not to take the risk of drinking this chemical.

Inhaling chlorine vapors, such as those released when you’re showering, has some known health effects. One study found that chlorine can cause nausea, cough, vomiting and even loss of consciousness – though this would only occur if exposed to high levels of chlorine.

Male adult holding a bucket for vomiting

Chlorine can also cause skin and eye irritation, and can dry out your skin and hair, according to a Live Science report. However, this issue is more common in swimming pools, which are treated with higher levels of chlorine than drinking water.

Aside from potential health effects, many people find the taste of chlorine unpleasant. You may want to test for chlorine if your water has a chemical taste, as you’re most likely dealing with a chlorine issue.

💭 How can I remove chlorine from water?

There are several methods of removing free chlorine or residual chlorine from your drinking water:

Activated and Catalytic Carbon Filters

The most affordable method of removing chlorine from municipal water is to use activated or catalytic carbon filters.

Activated carbon uses adsorption to trap chlorine and other contaminants across a large surface area. Free chlorine molecules are too big to fit through the filter’s pores, and are unable to pass through.

Activated Carbon

Catalytic carbon filters have an even larger surface area, which makes them even more capable of eliminating chlorine and combined chlorine from drinking water.

Carbon filters are used in whole-home filter systems, as well as countertop filters and pitcher filters, and even water bottle filters.

Reverse Osmosis

While carbon filters may only reduce chlorine levels, reverse osmosis can completely remove combined chlorine, residual chlorine and free chlorine.

This system sends water through multiple filtration stages at a high pressure, removing more than 99.9% total dissolved solids (TDS).

RO Membrane Media

Reverse osmosis systems feature a semi-permeable membrane, which is what makes them unique from other water filters. The membrane has tiny pores that block even the smallest contaminants from passing through.

Typically, reverse osmosis systems are installed underneath a kitchen sink. Whole-home reverse osmosis filters are also available, but these are far costlier.

Other Chlorine Removal Systems

There are several other methods of removing chlorine from water, including distillation and chemical neutralization. You can even remove chlorine by simply leaving it to evaporate from your water through exposure to oxygen in the air, or boiling your water to speed up the evaporation process. Some methods are more affordable than others.

If you’re keen to learn more about the best methods of removing chlorine from water, I recommend reading my full guide.

🙋 Frequently Asked Questions

Do I need to test my water for chlorine if I have a private well?

No. Free chlorine is only a water quality concern in public water. This chemical isn’t naturally occurring, so it’s highly unlikely that it will end up in your local groundwater. However, your well may still be at risk of chemical contamination from pesticides and herbicides, especially if you live in an area where agricultural activity is high.