Use Calcium Hypochlorite to Disinfect Water – Pool Shock

by Great Northern Prepper

Ok so Ive talked about this in my water preps page, but I wanted to do a post about it since it syncs with my “Cleaning Tech” Theme I did on Brooms on Monday! It also works very well to disinfect iffy water! Now you may even have a beautiful well on your property, but that doesn’t mean you don’t need to have this on hand…why? Because you never know where you’ll end up, who you might meet and want to help, and in tough times, being the guy who helped give everyone, or quite a few people access to safe drinking water will go a long way to build your credibility in a community or just ease your conscience in tough times and help other people.

Because yes we do all this to prepare ourselves and our families for times of troubles, but we also must be beacons during dark times, to help others be self-sufficient, so that they don’t need to turn to the government or other nefarious people for help, thus indebting themselves to them, and allowing a new cycle of dependency to begin. Ok off my soapbox and onto the topic.

What is Pool Shock?

Pool shock is a wonderful product, developed for people with pools, that chlorine smell in public or private pools, that’s pool shock. It disinfects the water and makes it ok to swim in without fear of waterborne diseases that love to run rampant in standing water (stops mosquitoes as well!). A side note…in any grid down or extremely “tough times” scenario will mean, especially in suburbs, a large percentage of the population no longer taking care of those thousands of pools in an area, which will then turn into algae infested muck ponds, breeding grounds for disease and insects. A Major health hazard.

Anyways, pool shock comes in many varieties, the main ingredient being CALCIUM HYPOCHLORITE, which is one ingredient to make bleach. There are many different ratios of CALCIUM HYPOCHLORITE (i.e 78%, 73%, 68%, 56%) I will only go over the 78% because that is what the information I have pertains to, as far as the others, you can look around on the net, I don’t truly know if you need to mix more with lower doses, etc.

One of main things you need to make sure of, for our uses in making bleach, is that the ONLY ACTIVE INGREDIENT IS CALCIUM HYPOCHLORITE! Many Pool shocks can include antifungal’s which could be dangerous for human consumption. So make sure whatever you buy it has only CALCIUM HYPOCHLORITE as the active ingredient. You also want to be sure that you buy only GRANULAR CALCIUM HYPOCHLORITE and not Liquid, the liquid variety breaks down, while the granular will store indefinitely, and since only a small amount is needed to produce a solution to treat water it only needs to be used in small amounts, not the whole lot.

How do I use it to Disinfect water?

Basically you mix a small amount with water which will make a Chlorine CONCENTRATE, this bleach concentrate will then be used to add to the water in specific number of drops. DO NOT DRINK THE CONCENTRATE! DO NOT DRINK THE CONCENTRATE! You add this to the water that needs to be disinfected!

Pool Shock comes in many different varieties of concentrate and this will dictate different ratios to use for making drinkable water.

Step 1: Mix “One Heaping Tablespoon”, About 1/4 ounce (15.16 grams) of the 78% High Test Granular Calcium Hypochlorite for every two gallons of water

You will now have a chlorine solution of around 75%

Step 2: You then add 1 PART Concentrate for every 100 parts Water that you want to disinfect

Now if you have 100 gallons to disinfect you will use 1 gallon of water, but most people don’t have that so for just one gallon you will use 1.28 Fl Oz. You can use something like this

This will measure more specific Fluid ounce measurements, remember a weight scale measures Weight Ounces not FLUID ounces.

1 Gallon= 1.28 Fl Oz

5 Gallon= 6.4 Fl Oz

40 Gallons= 51.2 Fl Oz

80 Gallons= 102.4 floz

(40-80 gallons is the average holding capacity of many rain barrels)

Step 3: Mix thoroughly (i.e. Stir with clean instrument) and let stand for 30+ minutes

Step 4: To remove “objectionable” chlorine odor, you need to “aerate” the water by allowing the water to stand exposed to the air for a few hours, or just pour it between clean containers a few times.

This is only to disinfect clear(ish) water that might have pathogens, if you have dirty muddy water you will need to strain it first.

HOW TO MAKE BLEACH

The bleach you buy in the store is made from SODIUM HYPOCHLORITE, which is slightly different, and the concentration is 50,000 ppm and the solution you just made above is 5ppm, so to achieve Concentration to use as Household Bleach for cleaning or to even disinfect water at that ratio you will need to dissolve it in much smaller doses of water.

Use the 1 “Heaping” Tablespoon measurement (1 Teaspoon 1/3 cup) to about 1 cup of water which will give a 5% bleach solution or 9 ounces to be closer to the 5.25% that many bleaches come in.

To make Bleach Bleach for household use go for about 1 teaspoon per Gallon to achieve the 500 ppm that household bleach is at. With this solution you can go with the 4-8 drops per gallon that you would use with normal household bleach to disinfect the water.

The “Drop Method” for using 5%+ Bleach is as follows

Available Chlorine / Drops per Quart/Gallon of Clear Water / Drops per Liter of Clear Water
1% / 10 per Quart – 40 per Gallon / 10 per Liter
4-6% / 2 per Quart – 8 per Gallon (1/8 teaspoon) / 2 per Liter
7-10% / 1 per Quart – 4 per Gallon / 1 per Liter

NOTES:

1 tbls=1 cup Bleach at 5% solution =625 Gallons (treated) water at 5ppm

1 tsp=1/3 cup Bleach at 5% solution=208 Gallons (treated) water at 5ppm

Roughly 453.592 grams per pound= 29.92 “heaping” Tablespoons (per pound of pool shock) = 18,700 gallons treated water

That’s 18,700 Gallons of treated water for $4.99 (if you go click on the picture link)

For $99.99 you get 24 pounds of the stuff, enough to treat 448,804 gallons of water. Pretty cheap and enough to Go around to help out for neighbors for a $100 dollar bill.

However If you want to make Bleach for cleaning like Clorox, It takes

1 tbls=1 Cup bleach at 5% solution

12 cups= 96 oz Clorox container

12 tbls= 1 Clorox Container

2.43 Bottles of Clorox per pound of Pool Shock

So if you are wanting to use Pool shock for Bleach as you would in the store it is still cost efficient and will keep indefinitely, while Clorox will lose effectiveness after 6 months roughly, and after that it loses 20% of its potency a year. So after 6 months + 1 year you will have a 4.8% solution, another year 3.84%, etc., etc.

Another good thing to do is to buy a Chlorine Test Kit with this you can test the ppm of your Chlorine solution, to make sure it is within the ranges you want it to be (ie 5ppm for disinfecting not to make Bleach). So you can make the disinfecting solution and add it to your water (i.e. 1.28 floz to 1 gallon), and then test it to make sure it is in the 5ppm range. This will not work for the bleach solution as that is around 50k+ ppm.


  • Mix outside, in a CLEAN PLASTIC container that has not held other chemicals in it.
  • Chlorine can be explosive or create chlorine gas when mixed with other chemicals ESPECIALLY OIL BASED SUBSTANCES! VERY BAD
  • Chlorine is an oxidizer so it will eat through metal, use Plastic
  • BE VERY CAREFUL this is a lifesaving measure, but if done improperly it could be life THREATENING
  • Chlorine should only be mixed and used as needed for Treating water before use, not for long-term storage. What i mean is that Pool Shock in its granular form will be good indefinitely, however when mixed with water it will need to be used within the month at the latest, or it will begin to degrade. This pertains to the water it is treated with as well. If you treat the water and seal it in a container the chlorine will degrade in a short period of time (could be within 2-3 months), and releases chlorine gas which could destroy the container its in and cause health problems.
  • The Chlorine will rust any metal objects it is near or around it so DON’T store with other preps in its packaged form (Remember this is usually used for pools, so it’s stored in a shed and used often, and bought as needed not stored for years in a basement). To combat this problem I read that a person stored the Pool Shock in Glass containers with a Glass top and rubber gasket, this stopped the Chlorine from leaching out and destroying his preps.