Pool Shock for Water Purification

Introduction: Pool Shock for Water Purification

About: David is a professional firearm instructor and Emergency Preparedness Author, He has 10 published works and his website is devoted to teaching individuals how to be better prepared for life and life's disaster…
If 2 is one and one is none, than I need another means of water purification other than my ceramic water filter.  I wanted something that stored indefinitely, was cheap, and most importantly kills all the bad junk in the water.

There are many preparedness blogs that discuss using hypochlorite to make bleach, but I had to wade through the differences between sodium and calcium hypochlorites and dosing amounts.  I found the sources below and decided on this method.

Many campers use bleach for water purification, but bleach degrades over time, so it only has an effective shelf life of 6 months to a year.  Dry High Test Hypochlorite (HTH) has no shelf life, and its cheap – a one pound bag (that will purify about 10,000 gallons of water) is about $5.00.  I spent a little more ($24.00) and bought a five pound jug (which is a LIFETIME) supply because it can be resealed.

I will tell you though that this is not a perfect solution, this stuff is a powerful corrosive and if you don’t store this properly you WILL have problems.

  • If it gets wet it can off-gas chlorine.
  • It can corrode metals
  • If certain petroleum products mix with the HTH it can spontaneously ignite in a way you do NOT want to see.

Granular Calcium Hypochlorite

Only use HTH Pool Shock that does not have any algicides or fungicides.  Ingredients should reads CALCIUM hypochlorite and inert ingredients.  Use a brand with at least 73% Hypochlorite.

For this video I used Poolife Turboshock, but feel free to use any brand you wish as long as it fits the perimeters above.

Before you begin mixing any chemicals in any way, please follow basic safety precautions.  Make sure you do this in a ventilated area.  Have plenty of water to dilute any mistakes.  Wear eye protection for splashes.  Lastly always mix the powder into the water NOT the other way around.

Add and dissolve one heaping teaspoon of high-test granular calcium hypochlorite (HTH) (approximately 1/4 ounce) for each two gallons of water.

The mixture will produce a chlorine solution of approximately 500 mg/L (0.0667632356 oz per US gallon), since the calcium hypochlorite has an 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 oz.) of stock chlorine to each 12.5 gallons of water to be disinfected.

To remove any objectionable chlorine odor, aerate the water by pouring it back and forth into containers to add air.

Chlorine Bleach

Common household bleach (unscented) contains a chlorine compound that will disinfect water. The procedure to be followed is usually written on the label. When the necessary procedure is not given, find the percentage of available chlorine on the label and use the information in the following tabulation as a guide.

Available Chlorine Drops per Quart of Clear Water

  • 1% needs 10 Drops
  • 4-6% needs  2 Drops
  • 7-10% needs 1 Drops

(If strength is unknown, add ten drops per quart of water. Double amount of chlorine for cloudy or colored water)

The treated water should be mixed thoroughly and allowed to stand for 30 minutes. The water should have a slight chlorine odor; if not, repeat the dosage and allow the water to stand for an additional 15 minutes.
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    7 years ago on Introduction

    So if one is in an evacuation situation and the only room in the pack is for a 32 ounce nalgene bottle and some powdered pool shock, how much of the pool shock should one add to purify a 32 ounce bottle? (I imagine it is miniscule.) I'm rather math challenged and having a hard time figuring this one out.


    Reply 7 years ago on Introduction

    the best I can tell looking through others math on the ratios for making chlorine and whatnot, it is actually a little hard to do it that way. The reason being that it is so strong. Some have said that it should take a (note one not multiple) granule of the pool shock to do 32 ounces of water. I am going to try this today and will let you know. I believe from what I was reading that the single granule was still a bit strong, I would make sure to leave the container open, or pour back and forth between two containers to airate it and decompose the bleach.


    Reply 7 years ago on Introduction

    update to the previous comment, in my 32 oz nalgene, a single granule made a light (little more than slight....) chlorine smell to it. This of course was with tap water. For clear or running water this might be a bit much on the side of chlorine in it, but for cloudy water it should be perfect. Do note that if you are ever using chlorine to purify water, you are supposed to let it sit for 30 minutes with the cap OFF so that it breaks down and leaves the water. While chlorine is relatively harmless in the levels that are used for pool purification, it should be noted that you still need to let it get out. Also while the author touched on it, don't store your calcium chlorite around other chemicals at all. Pool shock is not only reactive to petroleum products, but really just about anything liquid that isn't water. This isn't just a little deal like it will gum up or something either, usually the reactions involve explosions. Make sure to store it in an air tight non reactive container on the top shelf (mason jars work great for this due to their close size to the 1 lb packets).


    7 years ago on Introduction

    It's true that dry, sealed Calcium Hypochlorite will have a much long shelf life, but the "6 month expiration" of bleach is exaggerated. It starts out as 6% (typically) and should keep that strength for 6 months. Then what? Does it fall off a cliff and stop working?

    It begins to degrade (into table salt, NaCL) at 20% per year; Chlorox says to just use a little more. But look at your table - you can use 1% solution with 10 drops rather than 2 - the instructions suggest that if you don't know the concentration use 10 drops. That's in part to take into account the possible degradation of the bleach.

    This can happen faster above 70 degrees F, tho!

    So don't discount bleach entirely if it's over 6 mo old, if that's what you have; just use a bit more. But if you want to store disinfectant for many years - dry calcium hypochlorite is a good option! Thanks for telling people about it.