How To Disinfect Water With Pool Shock

Bleach is a common item in a preppers stockpile. While bleach has many important uses in an emergency situation, it has drawbacks: it expires quickly and it takes up a lot of space.

According to the Clorox website, the shelf life of regular Clorox Bleach (do not buy scented or splash-less or anything else for prepping) is:

The active ingredient in liquid bleach, sodium hypochlorite, is very sensitive to high heat and freezing, but under normal home storage conditions, it should still perform well for nine to twelve months. So if your storage conditions were either of these, then you will have irreversibly created salt and water.

Next question is intended use. The active does decline over time and to meet our EPA disinfecting requirements, you are probably on-the-edge; so I might add a little more than the 3/4 cup Clorox® Regular-Bleach per gallon of water for any disinfecting projects. For general cleaning, you should be fine since a little liquid bleach goes a long way.

Even with this drawback, I believe that storing bleach is an important part of emergency planning. You just have to constantly be vigilant about rotating through it. Some of the reasons to stock bleach include:

Pool shock, or Calcium Hypochlorite granules, is a better solution for long term storage of bleach and portability. You can use the granules to disinfect larger amounts of water, like the emergency water in your rain barrel. Calcium Hypochlorite stores for years without losing is effectiveness. A 1 lb bag that you can buy in most pool stores can disinfect 10,000 gallons of water and typically costs $7-$12 depending on the percentage of calcium hypochlorite in the mixure. The pool shock that you can buy in places like Walmart and Target typically have 52% percent calcium hypochlorite, you can get bags with 68% calcium hypochlorite sometimes, or if you live by a Leslie’s Pool Supply you can find 99% bags called Chlor-brite and/or order the Nava brand from our Amazon affiliate link.

*Reminder: According to the EPA boiling is the surest method to make water safe to drink and kill disease-causing microorganisms like Giardia lambliaand Cryptosporidium, which are frequently found in rivers and lakes. But boiling isn’t always possible so in those instances you are going to want to know how to chemically disinfect water.

disinfect water with pool shock

How To Disinfect Water With Pool Shock

Using calcium hypochlorite granules is a 2 step process. First you make the stock chlorine and then you mix it in the drinking water. Think of it as first making a bottle of bleach and then using that in the water.

Add and dissolve one heaping teaspoon of high-test granular calcium hypochlorite (approximately ¼ ounce) for each two gallons of water, or 5 milliliters (approximately 7 grams) per 7.5 liters of water.

The mixture will produce a stock chlorine solution of approximately 500 milligrams per liter, since the calcium hypochlorite has available chlorine equal to 70 percent of its weight.

To disinfect water, add the chlorine solution in the ratio of one part of chlorine solution to each 100 parts of water to be treated. This is roughly equal to adding 1 pint (16 ounces) of stock chlorine to each 12.5 gallons of water or (approximately ½ liter to 50 liters of water) to be disinfected.

To remove any objectionable chlorine odor, aerate the disinfected water by pouring it back and forth from one clean container to another. -directions from

One issue that arises when storing pool shock is that fumes do build up. You need to respect that this is a powerful chemical and you will need to be careful when opening it. Make sure whichever method you choose for storing this, you have it clearly labeled that there can be dangerous fumes upon opening it. 

Some suggestions for storing your pool shock. Leave the 1lb bags in their original packaging:

  • Vacuum seal the package with your food saver. This would probably be the best way to place it in a bug out bag.
  • Place in mason jar and vacuum seal the lid.
  • Place in 3 or 5 lb plastic food buckets (like the kind you would store rice or beans) but store the pool shock by itself.
  • Place in a clamp down glass jar with rubber ring.

No matter how you store calcium hypochlorite you should vent it at least once a year wearing protective gear and please, please, please remember to label it as though your children would come across it. And of course, keep it out of reach of children in the first place.


  1. If you’re worried about kids accessing these type of chemicals, spa chemicals come in bottles with childproof containers. They may not come in sizes that are as economical, but they are worth looking into if safety issue are of concern.

  2. I had no idea bleach had a shelf life. It never occurred to me that it might.

  3. Thanks for sharing this advice on disinfecting your pool! I think that having a supply of chemicals like calcium hypochlorite is always a good idea if you want to be prepared. I mean, your pool is a huge source of emergency water. If it’s disinfected properly, it can take care of your family for a very long time.

  4. If I use the shock from Walmart, should I use more than the required amount due to its lower concentration?

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