How to Test Chlorine in Water

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Chlorine is the main disinfectant in many swimming pools.

Chlorine is a naturally occurring element that is used to disinfect both pool and drinking water. It is important to test your pool water chlorine levels to ensure a sanitary swimming environment. You may also choose to test your drinking or filtered water for chlorine, as studies have suggested that ingesting large amounts of chlorine leads to artery damage and certain cancers. To test chlorine levels, you must use a chlorine test kit, available at any pool maintenance store.


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Step 1

Fill the vial with the water to be tested. If testing tap water, simply fill the vial from the tap. If testing pool water, submerge the vile upside down underwater with your arm inserted into the pool up to your elbow. Turn the vial over to allow the air bubbles to escape and water to fill the vial. Remove the vial filled with pool water from the water.

Step 2

Shake the vial gently to remove any water over the fill line marked on the vial.

Step 3

Place the appropriate number of drops of OTO solution into the vial with water. Refer to the chlorine test kit manufacturer instructions for the correct number of drops specific to your kit. To ensure full drops, squeeze the air out of the bottle with the bottle upright and then turn the bottle over and allow the air to rush back into the bottle.


Step 4

Replace the plug on the top of the vial if applicable.

Step 5

Stir the vial or shake if plugged. The water will turn a hue of yellow.

Step 6

Compare the color of the water with the color chart included with the chlorine test kit to determine the amount of chlorine present in the water.


Avoid spilling OTO on your skin as it may cause burns.