I did a bunch of research on this and thought I'd share it here (and save it here for my memory because this is the second time I've had to research this). While everything here is true to the best of my knowledge, I provide references so that you may seek out the original source and decide for yourself. Using any of this information is at your own risk and by continuing to read you agree to assume all responsibility and absolve me for any harm which may result from use of this information.

Intro:
Calcium Hypochlorite (I’ll call it CH for simplicity) is a powdered chlorine compound that has several advantages over household bleach. CH has a shelf-life of 2+ years [2] compared to 6 months for household bleach [1]. CH is cheaper, and more concentrated than bleach. However this does make it more dangerous.

Basic Instructions [11]:
To use the CH, start with the cleanest, clearest water you can get (filter or leave in a still container for a day and use a ladle to pull off the top).
Mix a heaping ½ tsp with 1 gallon of water to make a general disinfecting solution that is good for cleaning, sanitizing and hand-washing.
Then add 2.5 tablespoons of this solution to 1 gallon dirty water and let sit for 30 minutes to make potable (drinking) water.
If the water doesn’t smell faintly of chlorine after 30 minutes, add another tablespoon and wait 30 more minutes. Repeat until the water smells of chlorine.
To reduce the chlorine taste, pour the water back and forth between two containers for a few minutes, or sit the open container in direct sunlight for a few hours.

Where to get it:
The cheapest and most readily available source of CH is HTH Shock and Swim Poll Shock which is sold in 1 lb bags at wal-mart, home depot and elsewhere. They cost $3. Now, I know what you’re thinking “OMG I’m not drinking pool chemicals”, that was my first reaction. But the manufacturer even has EPA approval for using the product for the regular treatment of potable water wells and cisterns as well as emergency treatment of household drinking water [7-8]. This is a bit weaker than “pure” HC, so you will need to increase the amount used in the above formulas by 25-30%, but as the correct amount varies a bit anyways, this is no big deal, remember the smell test. 1 lb of this will make 100 gallons of cleaning solution and treat 100,000 gallons of drinking water. Now that’s some serious water treatment.
If you choose to use a product other than "HTH Shock and Swim" (not SUPER shock and swim), make sure it is EPA approved for use in drinking water. Reference #7 is a good place to start, I wouldn't use anything not on that list, but don't stop at the list, get that EPA number and google it. Go to the actual EPA documents (similar to reference 8 but for your product) and make sure it approved for emergency drinking water treatment.


Safety [5]:
Always read the MSDS before using any chemicals, this stuff is DANGEROUS. Eye protection is a must when handling CH. Gloves and a dust mask are not essential, but it's stupid not to use them, it's less than a dollar and might save you thousands in medical bills. Handle the powder in a well-ventilated area without wind. When dealing with corrosive chemicals it is always a good practice to have a 5 gallon bucket or sink full of water nearby to submerge your head, body or arms in case of an emergency.
When mixing CH add the CH to the water not vice-versa. It is important to go from dry to weak solution (less than 20% chlorine by weight) as fast as possible. If you only add a small amount of water to the CH it will release hazardous amounts of gaseous chlorine. If you feel a strong burning or stinging in your eyes, throat or lungs at any point, evacuate to fresh air immediately, chlorine can be deadly and was in fact used as a chemical warfare agent in WWI.
CH is a fire hazard when heated or mixed with certain organic compounds which will not be mentioned. Basically, don't let this stuff touch anything but plastic, glass and stainless steel and you'll be good to go.

Storage:
This stuff is dangerous, follow storage guidelines carefully.
keep away from children and pets and only store the minimum you might need (seriously a pound or two goes a long way). Store the powder in a cool, dark place (temperature and sunlight speed decomposition and can cause the material to combust or release chlorine gas over 125 F). Keep dry and in an airtight container (water or even high humidity will cause the release of chlorine gas).
At room temperature in a dry dark place, the storage life is over two years, the product can be kept for longer, but more will have to be used for the same results (the decomposed product is calcium carbonate, i.e. tums). Keep away from food, medicine and valuables because even in a sealed container, some gaseous chlorine will permeate and may ruin these items.
Polyethylene (LDPE or HDPE) containers are the preferred method of storage, as this is what the manufacturer’s packages are made of [3]. Nalgene makes HDPE containers that are available at most sporting goods stores (the squeezable Nalgene, look for HDPE, LDPE or UVPE marked on the bottom). Polycarbonate/lexan (i.e. the hard nalgenes) and PVC are not suitable for CH storage. PET, the material used for clear soda bottles is suitable if on a budget, but choose the thickest bottles possible [4]. Ideally you want to minimize the airspace in the container as chlorine gas will build up in that space and may overwhelm you when you open it.
I personally store 1 lb sacks of HTH shock-n-swim in 1 liter HDPE Nalgene bottles. With some work the sack can be put in the bottle without opening it, providing a double layer of protection. The first time I purchased some I put it in an old glass food jar thinking the rubber coating would keep the lid from rusting out… it didn’t even last a year.


More detailed info [8-12]:
The amount of chlorine required varies because minerals and organic compounds in the water will use up the HC before “free” chlorine can be released to attack waterborne pathogens. You can only smell the free chlorine, so if you can’t smell the chlorine, then you don’t have any free chlorine available. “pure” HC is about 70% free chlorine (700k ppm).
Household bleach is 5% free chlorine (50k ppm).
0.1%-1% free chlorine (1-10k ppm) for serious disinfecting and bleaching laundry.
OSHA & the EPA allows restaurants to clean dishes and prep surfaces with 200 ppm chlorine solution without rinsing afterwards.
Waste water is treated at 60 ppm.
Water that is clean, clear and soft (rainwater with a bit of bird poop) will require about 0.5 ppm chlorine to be drinkable.
Water that is clean, clear and hard (clean running streams, springs, wells) will require about 1 ppm chlorine to be drinkable.
Water hard with limited algae growth (lakes, cisterns) will require about 2 ppm chlorine to be drinkable.
Water with significant turbidity or organics (muddy, heavy algae) should be filtered through a sand filter if at all possible before being treated, but some directions allow for concentrations as high as 20 ppm for drinking water (I'd definitely let this sit out in the sun for a few hours and aerate the crap out of it).
Instructions seem to vary quite a bit and there is some tolerance for error, but most sources seem to agree that the smell test is the threshold for having the right amount of chlorine.

References:
[1] http://www.clorox.com/blogs/dr-laundry/ ... life-odor/
[2] http://www.hth.co.uk/wt_cal_hypochlorite.shtml
[3] http://www.borealisgroup.com/pdf/chemic ... dpe-ld.pdf
[4] http://www.cadshelters.co.uk/pdf/PET-tech-data.pdf
[5] http://www.homedepot.com/catalog/pdfIma ... 93c1d3.pdf
[6] http://en.wikipedia.org/wiki/Calcium_hypochlorite
[7] http://www.health.state.mn.us/divs/eh/w ... ection.pdf
[8] http://www.epa.gov/pesticides/chem_sear ... 100818.pdf
[9] http://www.who.int/water_sanitation_hea ... fs2_34.pdf
[10] http://www.who.int/water_sanitation_hea ... fs2_19.pdf
[11] http://water.epa.gov/aboutow/ogwdw/uplo ... r-2006.pdf
[12] http://www.talas-nyc.com/photos/msds/so ... lorite.pdf
[13] http://www.lifewater.ca/Section_15.htm

Random Notes:
(recorded here for my memory more than anything else)
Calcium hypochlorite loses 3-5% of its chlorine content per year in normal storage.
http://www.gewater.com/handbook/cooling ... lorine.jsp
Household bleach falls to 3% in 6-12 months, after that the data is inconclusive, it may hover there or continue to fall to 1% or less depending on the source:
http://web.mit.edu/watsan/Docs/Student% ... ti2002.pdf
http://www.jendodon.com/article/S0099-2 ... X/abstract
http://endoexperience.com/filecabinet/C ... chlori.pdf
http://www.forp.usp.br/restauradora/soda/sodaingl.html
Both CH and bleach photodegredate with half-lives measured in hours:
http://www.oltchim.ro/en/uploaded/2011/ ... .0_eng.pdf
http://www.inchem.org/documents/sids/sids/7778543.pdf

edited to include some information addressed below.

_________________
My Gear: IFAK - Blowout Kit - EDC & PSK

One caution to add is that your listed mixing formulas are only valid if the Hypochlorite bought is the same concentration as that for which you did the math. "Pool Shock" routinely is sold in concentrations from the low 50%s to about 70%. It's also mixed with various other chemicals in some formulations. It is obviously desirable to have a bag with the fewest other add ins (as they may well be toxic) and EPA/FDA/.gov stamp of approval for use in drinking water is a big plus.


Also, the smell test is not that useful as most people can detect free chlorine at somewhere between 0.2 and 0.5 PPM (mg/L). If you're trying to end up with a residual of 1-3ppm, the test will indicate too early.


Great info overall!

I found out the hard way that clorox bottles will disintegrate after a some time. Any idea of the storage life if sealed up as you describe? If airtight, I don't see the compounds breaking down to any significant degree, but I am not a chemist.

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Awesome post!! you have a lot of info there and some very good links.

Get a three or five gallon bucket with a Gamma lid. Leave the CH in the bags it came in until you are ready to use it. The buckets with a Gamma lid will keep it dry, contained and air tight. If you do need to break in to it only use as much as you need and seal it back up.

I would also recommend a pool free chlorine test kit, the kind with the dip strips that you match to the side of the bottle. They are cheap, last quite a while and are easy to use. They should help you get you concentration in the target zone you want. Much safer then a "smell test". I tried the kits with the drops, IMHO they were more of a PITA then they were worth.



A word of caution to anyone that is even thinking of storing LARGE amounts of Calcium Hypochlorite.

DO NOT STORE AT TEMPERATURES ABOVE: 52 Deg.C (125 Deg.F)
Storage above this temperature may result in rapid decomposition,
evolution of chlorine gas and heat sufficient to ignite combustible
products.


Below is an MSDS for Calcium Hypochlorite: (note this MSDS is based on 100%)

Material safety data sheet
Calcium Hypochlorite
1.Product Identification
Synonyms: Hypochlorous Acid, Calcium Salt; Losantin; Calcium Hypochloride;
Chlorinated lime
CAS No.:7778-54-3 Molecular weight: 142.98 Chemical Formula: CaCl2O2
Manufacturer: UNITCHEM CO,LTD
2-504,Guoxin Bldg A, The 2ND Street.TEDA,Tianjin,China
Tel: 86 22 66218316 Fax: 86 66218322
E-Mail: leo@unitewater.com
Web: http://www.unitewater.com
2.Composition/Information on Ingredients
Ingredient CAS NO 2nd grade· Hazardous
Calcium Hypochlorite 7778-54-3 100% Yes
3. Hazards Identification
Emergency Overview:
DANGER! STRONG OXIDIZER. CONTACT WITH OTHER MATERIAL MAY
CAUSE FIRE. CORROSIVE. CAUSES BURNS TO ANY AREA OF CONTACT.
HARMFUL IF SWALLOWED OR INHALED. WATER REACTIVE.
Potential Health Effects:
Inhalation:
Corrosive, Extremely destructive to tissues of the mucous membranes and upper
respiratory tract. Symptoms may include burning sensation, coughing, wheezing,
laryngitis, shortness of breath, headache, nausea and vomiting. Inhalation may be
fatal as a result of spasm inflammation and edema of the larynx and bronchi,
chemical pneumonitis and pulmonary edema.
Ingestion:
Corrosive, Swallowing can cause severe burns of the mouth, throat, and stomach.
Can cause sore throat, vomiting, diarrhea.
Skin Contact:
Corrosive. Symptoms of redness, pain, and severe burn can occur.
Eye Contact:
Corrosive. Contact can cause blurred vision, redness, pain and severe tissue burns.
Chronic Exposure:
Repeated exposures to calcium hypochlorite may cause bronchitis to develop with
cough and/or shortness of breath.
4. First aid Measures
Inhalation:
Remove to fresh air. If hot breathing, give artificial respiration. If breathing is difficult,
give oxygen. Get medical attention immediately.
Ingestion:
If swallowed, DO NOT INDUCE VOMITING. Give large quantities of water. Never
give anything by mouth to an unconscious person. Get medical attention
immediately.
Skin Contact:
Immediately flush skin with plenty of water for at least 15 minutes while removing
contaminated clothing and shoes. Get medical attention immediately. Wash clothing
before reuse. Thoroughly clean shoes before reuse.
Eye Contact:
Immediately flush eyes with plenty of water for at least 15 minutes, lifting lower and
upper eyelids occasionally. Get medical attention immediately.
5. Fire Fighting Measures
Fire:
Not combustible, but substance is a strong oxidizer and its heat of reaction with
reducing agents or combustibles may cause ignition. Thermally unstable; at higher
temperatures, may undergo accelerated decomposition with release of heat and
oxygen.
Explosion:
Sealed containers may rupture when heated. An explosion can occur if either a
carbon tetrachloride or a dry ammonium compound fire extinguisher is used to
extinguish a fire involving calcium hypochlorite. Sensitive to mechanical impact.
Fire Extinguishing Media:
Use flooding quantities of water as fog or spray. Use water spray to keep
fire-exposed containers cool. Avoid direct contact with water; reacts with water
releasing chlorine gas. Fight fire from protected location or maximum possible
distance. Do not use dry chemical fire extinguishers containing ammonium
compounds. Do not use carbon tetrachloride fire extinguishers. Do not allow water
run off to enter sewers or waterways.
Special Information:
In the event of a fire, wear full protective clothing and NIOSH-approved
self-contained breathing apparatus with full facepiece operated in the pressure
demand or other positive pressure mode.
6. Accidental Release Measures
Remove all sources of ignition. Keep water away from spilled material. Ventilate
area of leak or spill. Wear appropriate personal protective equipments as specified
in Section 8. Spills: Clean up spills in a manner that does not disperse dust into the
air. Use non-sparking tools and equipments. Pick up spill for recovery or disposal
and place in a closed container. Do not seal tightly.
7. Handling and Storage
Keep in a tightly closed container, stored in a cool, dry, ventilated area. Protect
against physical damage and moisture. Isolate from any source of heat or ignition.
Avoid storage on wood floors. Separate from incompatibles, combustibles, organic
or other readily oxidizable materials. Containers of this material may be hazardous
when empty since they retain product residues(dust, solids); observe all warnings
and precautions listed for the products.
8. Personal Protection
Personal Respirators:
For conditions of use where exposure to the dust or mist is apparent, a half-face
dust/mist respirator may be worm. For emergencies or instances where the
exposure levels are not known, use a full-face positive-pressure, air-supplied
respirator. WARNING: Air-purifying respirators do not protect workers in
oxygen-deficient atmospheres.
Skin Protection:
Wear impervious protective clothing, including boots, gloves, lab coat, apron or
coveralls, as appropriate, to prevent skin contact.
Eye Protection:
Use chemical safety goggles and/or a full face shield where splashing is possible.
Maintain eye wash fountain and quick-drench facilities in work area.
9. Physical and Chemical Properties
Appearance: White or grayish-white powder.
Odor: Chlorine-like odor.
Solubility: Soluble in water; reacts, releasing chlorine gas.
10. Stability and Reactivity
Stability
Rapidly decomposes on expsure to air. May decompose violently if exposed to heat
or direct sunlight. Thermally unstable; decomposes at 177C(350F).
Hazardous Decomposition Products:
Calcium Hypochlorite gives off oxygen, chlorine and chlorine monoxide.
Incompatibilities:
Calcium hypochlorite is a strong oxidizer. Reacts with water and acids giving off
chlorine gas. Forms explosive compounds with ammonia and amines. Incompatable
with organic materials, nitrogen compounds and combustible materials.
Conditions to Avoid:
Heat, flame, moisture, dusting, sources of ignition and shock, and incompatibles.
11. Disposal Considerations
What ever can not be saved for recovery or recycling should be handled as
hazardous waste. Processing, use or contamination of this product may change the
waste management options.
12. Transport Information
Proper Shipping Name: Calcium hypochlorite
Hazard Class: 5.1 UN/NA: UN1748 IMDG:PAGE5137


IF STORED WRONG OR IF IT COMES IN CONTACT WITH OTHER CHEMICALS OR HEAT IT CAN AND WILL KILL YOU AND ANYONE AROUND YOU.

Also if you do not use the proper personal protection equipment it can and will harm you.

If you are going to store a couple of pounds of the stuff, you should be ok with some common sense. But keep in mind that it can and is still very dangerous stuff.

1-pound bag of calcium hypochlorite can disinfect up to 10,000 gallons of drinking water. That’s around 5 gallons/day for one person for 5 1/2 years! (Now keeping in mind that the number in this will depend on the amount of or percentage of CH in the product you have.)

The reason I put up an MSDS that was for 100% HC is so you can see an MSDS that is not full of "fluff" and watered down safety concerns. 30-80% HC is just as dangerous as 100% HC.

In no way should anyone take this post as telling you to not use or store HC. I just want to drive the point home that this stuff needs to be taken very seriously.

I have two pounds of HC in a 3 gallon bucket with a Gamma seal lid on it. It is taken outside every month or two and checked for gas build up and dampness. I also have a digital thermometer sitting on the bucket that tells me the temperature now and it also has a high and low temp setting (has an alarm too for that). So that way I know exactly what the highest and lowest temperature the bucket was exposed to was. I have been using this system for almost ten years.

_________________
Stuck behind enemy lines in the peoples republik of Massholes!

"Ense petit placidam sub libertate quietem"
By the sword we seek peace, but peace only under liberty.
Kinda funny, for a state that takes and regulates your liberty's to such extremes to have this as the state motto.
ΜΟΛΩΝ ΛΑΒΕ
Sic Vis Pacem, Parabellum
Deus Vult

If you are talking about bleach this if from the Clorox web site:


"It’s important to keep track of how old your bleach is because yes, bleach doesn’t last forever! When Clorox® Regular-Bleach is stored between 50°F and 70F° and away from sunlight, it will maintain label strength of the sodium hypochlorite active for up to 6 months (at this point hospitals should replace it). After 6 months it starts breaking down into salt and water, but will still perform well for home consumer cleaning needs for up to a year. Since it’s always diluted before use, you can just use a little more. Beyond a year, it should be replaced because the rate of decomposition into salt and water really speeds up, a big part of why it’s so environmentally friendly."

If you have a pool test kit that might work to tell you the PPM level in the bleach.

_________________
Stuck behind enemy lines in the peoples republik of Massholes!

"Ense petit placidam sub libertate quietem"
By the sword we seek peace, but peace only under liberty.
Kinda funny, for a state that takes and regulates your liberty's to such extremes to have this as the state motto.
ΜΟΛΩΝ ΛΑΒΕ
Sic Vis Pacem, Parabellum
Deus Vult

This is a great post!

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Duco Ergo Sum



Hall of Fame Forum


Forum Rules Link

Thanks for your comment. I should have put that information about selecting the correct item, but I was really intending to mainly promote specifically the HTH Shock and Swim (NOT HTH SUPER shock and swim), as it is the only specific product I have researched. Because this product is available at both Home Depot and Walmart, I can't imagine many people will not have access to it. If you use any other brand of pool shock, please, please, please check that it is EPA approved for drinking water use. Some of the products (like the super shock and swim) have algacides and or other chemicals that are not safe for human consumption.

As for the 50%-70% variance and the chlorine smell test, I am basing my statement on numerous sources including the EPA, WHO and others that state to keep adding till you can smell the residual chlorine. I was also under the impression that you were seeking something like 0.5 PPM residual after the impurities in the water absorbed the rest, so while you might need to add 1-3 PPM to sanitize the water, much of that binds immediately with organic and inorganic compounds in the water and never results in free chlorine (which is the only type you smell). However, perhaps you have professional experience to indicate otherwise? If so I'd appreciate a reference so that I may update my information.



I really have no idea, I have just started this storage method as the glass jar totally failed and I decided to do more research storage methods instead of just guessing. I am sure this will last at least two years and likely much longer because the manufacturers packaging does not crumble on this time span and it is also made of polyethylene.

I think minimizing the air space in the container, using the thickest LDPE/HDPE container possible and keeping it cool, dry and fully sealed will extend the shelf life significantly. BUT even airtight bottles are not truly airtight, as all plastics have some significant air permeability (hence why balloons shrink and bottled sodas lose their fizz over time even though they are "airtight"). This is also one of the reasons aluminized mylar is used for long term storage of food, the aluminum layer greatly reduces the permeability. Perhaps this is a way to further extend the storage life, but I only intend to store one pound... and at $3 a pound, I'll just replace it every few years.

_________________
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Thanks for the comments, I updated the original post to stress safety a bit more.

I like the chlorine test strips, I'll have to check for those.

I personally don't like the bucket idea as it increases the volume of air near the product and provides a greater space for the build up of chlorine gas. Much like when storing food, dead air space is your enemy.

However your thermometer and regular maintenance schedule is to be applauded, I wish I could inspect my preps monthly :/.

_________________
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Thanks for posting this thread. Very informative. I had no idea, really, about this.

_________________
President ZSC011
Part Viking, Part Siamese

It's been a few years since Organic Chem. I also worked at a community center for a couple years, and dealt with pool shock as part of my "keep the pool clean and running" duties.
It's entirely possible that I'm way the shit off base, but here's what my brain is telling me at the moment:

This is because pool shock is typically a concentrated solid. Household Bleach is a diluted liquid.
Solid vs. Liquid is the reason that shock has a longer shelf-life than bleach.

Bleach is caustic, even in low-level Clorox-type concentrations. It's just a matter of time. being airtight only prolongs it because the water can't evaporate (allowing it to concentrate). Leave the cap off in the sun for a bit on a warm day. Evaporate out 2/3 of the water. If that shit doesn't clean/kill/purify whatever you apply it to, it just wasn't meant to be.

Calcium Hypochlorite essentially IS bleach. Clorox brand is SODIUM hypochlorite. The only different this makes is Ca++ (calcium) holds two hypochlorite molecules (the active part) and Na+(sodium) holds just one. But that Ca++ holding two takes up double the space of a Na+ with one. In the end, it also washes out. I could get into moles per liter and all that, but I'm feeling a bit lazy.

Personally, if I'm doing anything like this for water purification/storage, I'm going with Clorox-type bleach. One drop per Liter, let sit a while, and all is well.
Anyhoo. That's my .02 as best I can put it in writing.

Edit: I'm am BY NO MEANS knocking your ideas. The solid powder option can be a great space-saving measure, just be sure to get concentrations right. That shit is WAAAY more concentrated that household bleach.

1) You'll probably need to contact the manufacturer of the strips for a final verdict on the exact model you're using, but the ones I just bought have a 2-year shelf life if the bottle is still sealed from the factory. As soon as you pop the top, you have 90 days to use all the strips. I'm sure that varies by brand though.

2) Make sure you're getting a pool test kit that tests Free chlorine. Some of them test Total chlorine and that's no good for sanitation.


As far as my comments on smell detection level, that comes from two things. First, that's the values published in research journals. Second, my wife's graduate work was in odor detection and identification. The reason they mention the smell test is that it means there's at least some chlorine residual and it's the best test you can do without equipment. It's better than nothing in other words.

Regarding the desired concentration, any free chlorine after long exposure is a sign the water itself has been sufficiently sterilized. However, the EPA targets 0.5-3.0ppm residual free chlorine in municipal water because the things with which the water comes into contact next might not be sterile. In other words, they leave a little extra chlorine in the water to help sterilize your faucet, etc. In a survival situation, it's reasonable to assume that your canteen, drinking cup, bowl, and hands might not be meeting the highest standards of sanitation and therefore a little extra chlorine may well be desireable.

Yeah, but I was hoping the OP had come up with an easy way to mitigate stray voltage from shocking people when they get in-or-out of a swimming pool.

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............................................................................................................................................................................................

There are a couple of things to bear in mind here.

If you are buying shock you will see varieties with and without extra algaecide. Avoid the ones with algeacide if you want to use it for potable water.

Not all algeacides are safe for human consumption

The same for bleach. Make sure it is unsented bleach. The perfumes that they put in bleach will contaminate potable water.

A final thought. Those of you with pools you should consider a way to harvest that nice 10,000+ gallons of water for emergency use.

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Not sure this advice works... the increased temperature will result in increased decomposition / evaporation of the chlorite ions as well. Not to mention UV will cause the chlorites to decompose as well... You should just use more of the bleach, not try and concentrate it.

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First off, this thread is great. Good information.


http://blogs.howstuffworks.com/2011/03/ ... ituations/
GunsUp is right. If you want your bleach to be completely ineffective at killing anything, let the bleach sit outside on a warm day with the cap off. The chlorine just does not stick around for very long. If you want your bleach to last longer, keep it sealed and cold.

GunsUp / Liff - Yeah I'm not sure where I was going with that point. I was a bit out of it on Friday. I think I may been trying to say something about why liquid bleach will degrade the plastic jugs, but I'm not sure.

Thanks for pointing out the errors in my obviously flawed arguments

Just a couple of points to help out the conversation. I currently am a Certified Pool Operator/Aquatic facilities operator for my job. I operate a commercial pool and have for the past 4 years.

Calcium hypochlorite is a chemical I use daily. Cal-hypo a very powerful chemical in dry form and has to be treated with a great deal of respect: for instance, if it comes in contact with an acidic solution of pH <6 it will release chlorine gas. Pulmonary edema is not going to be fun for anyone.

Also, do not confuse Cal-hypo with Chlorox bleach - they aren't the same. Chlorox is sodium hypochlorite, NaClO where Cal-hypo is Ca(ClO)2, twice as many ions of hypochlorite per mole of chemical. Secondly, cal-hypo is solid and stable under dry shipping conditions, sodium hypo is a liquid solution which degrades into saltwater over time. Seeing as the molar availability of hypochlorite is different between the two chemicals, you cannot equate the two. Cal-hypo is typically 63% hypochlorite by weight if I recall correctly,and I believe the equivalent concentration in sodium hypochlorite is higher by weight. After my lunch break is over I may amend my statement. The advantage of Cal-hypo is that it can be stored indefinitely in dry form.

More importantly, sanitation is a product of contact time- concentration in relation to time corrected for temperature. Make sure before you begin you are aware how long and at what concentration you have to run at the temperature of your water.

_________________

Great post... not enough people know about pool shock for drinking water purification - not everyone knows that regular household bleach is useless after a couple of years, max.

If you are going to store calcium hypochlorite, you have to take some pretty thorough precautions. The stuff emits vapors over time. Those vapors are capable of penetrating other sealed containers. Such as boxes of stored food. The exposed food tastes nasty and is probably at least partly toxic. Ask me how I know...

Also, the vapors are corrosive - by which I mean it rusts iron/steel and corrodes other metals like aluminum. Again, ask me how I know. You don't want tools, canned food, electronics or other prep gear anywhere near this stuff. I would definitely not keep any in my car.

As per my last post, a little looking around the interwebs reveals that the World Health Organization's recommendations for Cal-hypo are as follows: 4 drops of a 1% solution of CH added to 1 L of 25C water ( 77F) should have a contact time of 30 minutes. Increase the contact time 30 min for every 10C below this temperature e.g. 10C would require a contact time of 1 hour.

What is a 1% solution? 100 parts per million (ppm). Typically sodium hypo sold as bleach is 500 ppm or 5% bleach. But since more hypochlorite ions are delivered per mole of solution, this is plenty.

Most viruses and bacteria are treated this way BUT not Criptosporidium and some parasites. According to my CPO handbook, Crypto requires much longer contact times - on the order of 12 hours at 20 ppm shock, standard response for a fecal discharge in a commercial pool. Iodine is better at treating turbid water than cal-hypo.

In my opinions, cal-hypo is a go-to solution for larger quantities of water sanitation. It doesn't beat boiling or distillation, and in small quantity iodine or filtering is a better solution than cal-hypo. But if you need a shelf-stable chemical that can treat enough water for the tribe, and you have a cistern or rain catchment system, this might be a good option.

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A VERY GOOD POSTING ...... but a possible danger not covered ..... calcium hypochlorite reacts with certain petro chems ..... not going into any details for certain reasons .... but do not store anywhere close to fuels or oils of any kind .....

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Illini Warrior

Oh sure. CH is a very strong oxidizer, which is why in a pool shock capacity, it works not only as a sanitizer, but a flocculant. Any petrochem would be strongly oxidized, aka burn, with contact with dry CH. As a lad, my friends and i would mix all kinds of things we shoudn't have, and CH is an incredible oxidizer. But that is now illegal and was dumb. Shame on me, regardless of how fun it was.

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You'll find that the term "organic compounds" is a more general term that includes those petrochemicals that i am certain you are referring to. But as the reaction is quite violent, I suppose it is worth restating for safety sake.

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My Gear: IFAK - Blowout Kit - EDC & PSK

GunsUp, great thread and bravo for "original sources"!
Please "sig" this thread.

When/if you get the chance, this would make a great Wiki topic.


GlockASP, thanks! That's a level of thoroughness worthy of your avatar, my hero "Scrat".
What's the model of your min-max thermometer?
Pictures would also be helpful.

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Just FYI ...

1.) If you store HC in a mylar bag, the mylar is gone in 24 hours and you have a fully transparent bag.

It also escaped from the inner mylar bag to destroy the outer mylar bag coating within 24 hours.

2.) Gamma buckets do no seal well at all. Leave one out in the rain fro a few weeks if you want to see what I mean.

3. When I worked at a pool, we had a spray bottle of ammonia that we sprayed into the machine room because if there was a chlorine gas leak you would be dead before you expected anything.

http://www.awwa.org/publications/opflow ... 020163.pdf


Thanks for the great info...