Purify Water with Pool Shock

Preparedness is important to a lot of people. With seemingly unpredictable weather patterns that plague nearly all of the country and frightening news stories constantly tracking across the bottom of our TV screens, it’s hard not to worry about resources we have access to in case of such an emergency. Water is the most valuable resource we have and having a store of drinking water or a means to purify it is important. If you’re a pool owner, you may already have a means of purifying drinking water at home already: granular pool shock.

While there are purification tablets and other more traditional means for making water potable, many survivalists stock liquid bleach as a means to create drinkable water in case of an emergency. Instead of stocking bleach, you can give yourself a lot more room (and avoid unnecessary complications) if you purify water with pool shock.

The Problem with Bleach

There are a few problems with storing common liquid bleach. While it’s a powerful disinfectant and sanitizer that is useful in many situations, it takes a lot of room to store and its shelf life is only 6-12 months before it starts to lose efficacy. From Clorox: “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.” Another issue is that concentrated bleach is not meant to be used to purify water. Products like Clorox Ultra are sometimes the only option available and it’s not recommended for water purification purposes.

All over the internet there are survival preparedness blogs and forums that suggest the use of pool shock and explore the standards for use. The EPA even says explicitly states that you can use granular calcium hypochlorite [pool shock] to disinfect water. However, the EPA’s instructions are a bit convoluted and their website uses a bunch of instructions that include the words “approximately” and “roughly” on more than one occasion.

An article over at BackdoorSurvival where the author conducted her own testing proved particularly illuminating. Here is a summation of her findings.

First, there are different kinds of pool shock that come with varying percentages of calcium hypochlorite depending on the brand you buy. Essentially, the percentage doesn’t matter as long as it’s within reasonable range of the EPA standard and 68% or higher. It’s important that the pool shock you choose does not have other active additives or it may not be safe when diluted.

This particular tutorial describes how to make a solution out of pool shock that can then be used to purify water. In a sense, it’s like making your own bleach with an infinite shelf life.

Grab some supplies before starting: eye protection goggles, rubber gloves, an empty container in which you can store the solution, funnel, shot glass (or small measuring device), measuring spoons, and permanent marker.


  1. Clean the container and verify its capacity. Make it easier on yourself by choosing a round number like one gallon—even if your vessel can hold more—and filling it accordingly. The old Clorox container the author used has a 1.42 gallon capacity but she only made 1 gallon of stock to keep it simple.
  2. Put on your protective gear, add the water to the solution bottle you’ve chosen being careful to make your measurement exact (whether you do one gallon or another amount).
  3. Measure out 1 level (NOT heaping) teaspoon of pool shock and add it to the water. Put on the cap and swish it around to mix thoroughly. DO NOT shake. You can do a smell test—it should smell much like standard bleach.
  4. To use this solution to purify drinking water, add 1 part chlorine solution to 100 parts water, according to the EPA standards. So take the ounce capacity of your chose vessel (say 64 ounces) and divide it by 100. This would be .64 ounces or approximately 2/3rds ounce. The EPA uses the word “approximately” so you know that having on-the-nose measurements aren’t paramount. Measure your diluted pool shock in a small shot glass or other measuring device.
  5. Pour the solution into the water and not the other way around. Be careful to not let the solution on yourself or surrounding surfaces.
  6. Prepare the newly purified water. The author drank her water successfully and did not have any adverse effects. If your water has a smell after adding the solution, you can aerate the water by pouring it back and forth between two clean containers.
  7. According to this particular author, the water did not have an objectionable smell or taste and was quite palatable.
  8. Label your shock solution. It’s powerful and should last and be stable on your shelf for as long as you need it. Label the container with a permanent marker and include all necessary information/instructions. The author wrote “1 tsp pool shock per gallon of water—dilute 1:100, take volume of container and divide by 100.”
  9. Store the pool shock granules you did not use in a non-corrosive container like a glass jar. You can just clip the existing bag closed and put it inside.


You want to keep remaining pool shock in a cool, dry area that is well-ventilated. Store it away from combustible or flammable products and keep the packaging clean and away from contamination. Do not store anywhere that the average daily temperature exceeds 95° F which may result in rapid decomposition, development of chlorine gas and heat sufficient to ignite combustible products.


It’s important to remember that pool shock solution is a good product for emergency preparedness but should not be your first line of defense. It’s important to carry a traditional supply of water purification liquids and tablets that are pre-measured and easy to carry with you. Pool shock solution is meant to work in an emergency. Remember that pool shock is a powerful and potentially toxic chemical if not used or handled properly although it is much safer in its diluted form.

One pound of packaged pool shock has an almost infinite shelf life and can treat ten thousand gallons of water. TEN THOUSAND! Remember, it is a product meant to care for swimming pools with great capacities so it makes sense that a little goes a very, very long way. It’s a small investment that is worth it.

Has anyone tried this at home? Does anyone plan on using it in the future?

Bromine: Pool Sanitizer FAQs

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