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Swimming Pool Chemicals

What are swimming pool chemicals?

Swimming pool chemicals include various kinds of disinfectants and sanitizers which work to control the growth of certain kinds of algae and bacteria in the pool water. Swimming pool chemicals may also be used in hot tubs, spas, wading pools, and whirlpools.

Various kinds of disinfectants and sanitizers are used but the "chlorine" type is the most common. The chlorine usually comes from "chlorinating agents" that release chlorine when they are dissolved in the water. Chlorine gas may be used in large pools.

The chlorine-based disinfectants may be called "chlorinating liquid", "dry chlorine" or "liquid chlorine". The so-called "dry chlorine" is actually chemicals in granular or tablet form while "liquid chlorine" and "chlorinating liquid" are solutions of these chemicals dissolved in water. This document will summarize the safe use of these chlorinating agents but it will not discuss the use of chlorine gas.

What are the types of chlorinating agents?

There are two main types of chlorinating agents:

  • inorganic chlorinating agents such as calcium hypochlorite, lithium hypochlorite, sodium hypochlorite, and
  • organic chlorinating agents such as trichloroisocyanuric acid, potassium dichloroisocyanurate, sodium dichlorocyanurate [as anhydrous or dihydrate forms].

Organic and inorganic chlorinating agents are not compatible with each other. Many incidents occur when the same scoop or pail is used for both chemicals with out cleaning them or when adding one product after the other or in the pool chlorinator. Mixing or cross-contamination of these chemicals can form an explosive mixture.

Why should I be careful when using and storing these chemicals?

Swimming pool chemicals can also be oxidizers and corrosives.

Oxidizing materials (such as calcium hypochlorite) have the ability to react chemically to oxidize combustible (burnable) materials. To be an "oxidizer", the material itself provides oxygen which combines chemically with another material in a way that increases the chance of a fire or explosion. This reaction may be spontaneous at either room temperature or may occur with slight heating. Thus, oxidizing liquids and solids can be severe fire and explosion hazards. For more information about oxidizing materials and how to work with them safely, please see the OSH Answers section on Oxidizing Liquids and Solids.

Some pool chemicals can also be corrosive. Corrosives are materials that can attack and chemically destroy body tissues on contact. Corrosives can also damage or destroy metal. The effects on tissues and metals depends on what the corrosive agent is and how concentrated it is. They can begin to cause damage as soon as they touch the skin, eyes, respiratory tract, digestive tract, or the metal. MSDSs or product labels should be consulted for the specific effects on tissues or metals and for procedures to follow in cases of spills or splashes. For more information about how to work safely with corrosive chemicals or materials, please see the Corrosive Materials section.

What are some tips for handling chlorinated swimming pool chemicals?


  • Read and follow instructions carefully. If there is anything you do not understand, ask your pool chemical supplier for help. (Also see How Do I Work Safely with Corrosive Liquids and Solids?)
  • Keep all chemicals out of the reach of children and pets.
  • Containers should always be kept closed when not in use.
  • Use separate, clean metal or plastic measuring cups for each chemical to transfer or measure chemicals. (Scoops should not be made of wood.)
  • Wear appropriate protective equipment and clothing including goggles, gloves and footwear.
  • Protect chemicals from moisture and water - such as a cup of water (or coffee!). Even putting the wet scoop back into the pail may cause a reaction.
  • Always add the chemical to the pool water - never the other way around (never add water to the chemical) unless instructed to do so on the container label.
  • Wash your hands thoroughly after handling any chemicals.
  • Use or handle chemicals in well ventilated areas only.


  • Do not use contents of unlabeled containers.
  • Do not mix different chemicals together.
  • Do not put spilled chemicals back into their containers.
  • Avoid touching the undiluted chemicals with your hands.
  • Do not smoke when handling chemicals.
  • Do not expose to heat or flame.
  • If a fire breaks out, do not use a "dry chemical" fire extinguisher. Only use large amounts of water. If you cannot extinguish the flame immediately, leave the area and call the fire department.

What are tips for safe storage of pool chemicals?

  • Store in a cool, dry place away from sunlight.
  • Keep out of reach of children and pets.
  • Store chemicals in the original containers.
  • Be sure your storage area is well ventilated. Vapours may build up inside containers in high temperatures. Nose and throat irritation or more serious respiratory problems (cough or shortness of breath) may result if inhaled.
  • Never store oxidizers and acid near each other. Oxidizers will release chlorine gas if they come in contact with acids.
  • Do not store liquids above powders or solids. Do not stack containers.
  • Do not store materials or chemicals above your head.
  • Do not store pool chemicals near gasoline, fertilizers, herbicides, grease, paints, tile cleaners, turpentine, or flammable materials. This tip is especially important when pool chemicals are stored in sheds or small storage rooms.
  • Do not reuse containers. Wash out the container when empty and then dispose of it.

How should I clean up small spills?

Any spills larger than 50 kg should be handled as an emergency and the fire department called immediately. If in doubt of what to do, call the fire department or your local chemical spill emergency response centre.

Before cleaning up a small spill:

  • Make sure that the material is dry and has not mixed with other chemicals.
  • Do not clean if the chemicals has mixed with other materials (such as grass, paper, etc) or if the material is reacting (hissing, bubbling, smoking, gassing, burning) or the containers are bulging.
  • If there is any sign that a chemical reaction is happening, evacuate the area immediately and contact your local fire department for help.


  • Wear protective gloves, boots and aprons made of butyl rubber or neoprene (or other material specified in the MSDS).
  • Wear safety goggles - goggles offer better protection against liquid splashes and airborne dust than glasses. Goggles that are called '"indirectly vented" or "non-ventilated" chemical resistant will help prevent liquids from splashing and reaching the eyes. Face shields may be worn in combination with the goggles.
  • Ventilate the area if indoors.
  • Carefully place the spilled material in a clean, dry plastic bag or container. Place this filled plastic bag inside another bag when finished.
  • Keep an eye on the material once it has been picked up. A reaction may be delayed.
  • Dispose of the material according to manufacturer instructions and according to local regulations.


  • Do not place spilled material back in the original container.
  • Do not generate dust when cleaning up a powder or solid. The dust may react with the moisture on your skin and cause injury.
  • If using a container to hold the spill, do not seal.

In general, what do I do if someone needs first aid?

  • Immediately remove the victim from the source of contamination.
  • Quickly remove contaminated clothing, shoes and leather goods.
  • As quickly as possible, flush the contaminated area with (preferably) lukewarm, gently flowing water for at least 15-20 minutes (longer flushing time is desirable for corrosives).
  • Have someone call for medical help or advice, if required.

Tip - Consult the material label and any product literature (such as a Material Safety Data Sheet (MSDS)) in advance for information on appropriate first aid procedures - be prepared!

For more information please refer to the first aid section of our OSH Answer document on chlorine.

General information on first aid for chemical exposures is also available.

For more detailed information, you may wish to view the CCOHS publication The Material Safety Data Sheet - A Practical Guide to First Aid.

Document last updated on June 2, 2011

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Although every effort is made to ensure the accuracy, currency and completeness of the information, CCOHS does not guarantee, warrant, represent or undertake that the information provided is correct, accurate or current. CCOHS is not liable for any loss, claim, or demand arising directly or indirectly from any use or reliance upon the information.