An Alternative to Calcium Hypochlorite, by TLS

I have read articles and posts, as well as listened to preppers discuss the use of Calcium Hypochlorite (Cal-Hypo) as a water sanitizer in The-End-Of-The-World-As-We-Know-It (TEOTWAWKI) situations. I owned a swimming pool business for over 20 years, and during that time I used Cal-Hypo, Sodium Dichloro-S-Trianzinetrione (Dichlor), and Sodium Trichloro-S-Trianzinetrione (Trichlor) extensively in both commercial and residential swimming pools. I also installed and maintained many salt-chlorine generator systems. Every time I read about someone planning to use Cal-Hypo for long-term storage to provide water sanitation in TEOTWAWKI, I cringe. Cal-Hypo has many serious shortcomings. The disadvantages are:

  1. Cal-Hypo degrades and loses potency over time. It has a limited shelf life.
  2. Cal-Hypo gives off corrosive chlorine gas as it deteriorates.
  3. Cal-Hypo is a powerful oxidizer that can cause fires or worse, if used or stored improperly

I would never rely on storing Cal-Hypo long term for a disaster or survival scenario. Cal-Hypo is unable to handle long-term needs because of its short shelf life. Sure, it is very effective in normal times but only if you can always run out to buy more. As with many perishable commodities, the day will come when your stockpile will expire and become nothing more than a useless, white powder. Those that rely on Cal-Hypo to provide lifesaving sanitation, in a long-term emergency situation, will find themselves ill-prepared.

Cal-Hypo loses its potency from the moment it leaves the plant. It has a limited shelf life, and little can be done to change that. Its shelf life varies based on the quality of the product and the temperature at which it was stored. At higher temperatures, Cal-Hypo breaks down even more rapidly. When Cal-Hypo is purchased, one does not know how long it has been in the supply chain and to what temperature levels it has been exposed. The pail of HtH Cal-Hypo down at the local big box store will probably only be good for about two years. Additionally, that pail sitting on the shelf with a big discount sale sign might have been a left-over from the previous season. Repackaging Cal-Hypo will not make it last longer. At best, it is an exercise in futility.

As Cal-Hypo breaks down, it gives off gaseous chlorine. Chlorine gas is nasty stuff. It severely corrodes metals, destroys natural fibers and some plastics. I opened many old containers of Cal-Hypo and was greeted by a noxious, yellow, gas cloud. It’s not very pleasant, I assure you! Cal-Hypo is a very powerful oxidizer that can give you a really bad day, if handled improperly. Just read the label on any Cal-Hypo container.

If the disinfection of drinking water is part of your long-term preps, then I recommend that you check out the CDC website.

There is a lot of useful information, on drinking water sanitation, in the FAQ section. The subject that should be of the greatest interest to a prepper is the section on hypochlorite generators. The CDC refers to commercial-sized hypochlorite generators that cost into the six figures. However, a prepper can make his own small-scale sodium hypochlorite generator for about $2,500, if he already has an off-grid electrical supply that can provide 10 amps at 120 volts. This can be done using readily available components from most swimming pool retailers. In the late 80’s and early 90’s, I was an authorized dealer for Lectronator, an early in-line swimming pool chlorine generator system. The patent ran out several years ago. However, there are now several different makes on the market that are similar to the Lectronator.

How does a chlorine generator work?

A chlorine generator works by passing a saltwater brine solution through an electrolytic cell. Inside the cell, there are several parallel plates made of titanium that act as cathodes and anodes. As the electrical current passes across the plates, chlorine is freed from the sodium to create a hypochlorite solution. The Lectronator was simple in design. It had the electrolytic cell that was mounted in the filtered water return line, a water flow detector, and a power supply. The unit that is currently on the market, and one that I personally prefer, is Pentair Intellichlor. It is similar to the Lectronator but has a more advanced control system, and it has the ability to read salt levels. Swimming pool chlorine generators are very similar in design and function to the large-scale chlorine generators referred to by the CDC.

How to make your own chlorine factory.

To create your own mini-sodium hypochlorite factory, the four major components needed are:

  1. A water storage tank that holds about 200 gallons (a cube-shaped tank is easiest to plumb into),
  2. A circulation pump, at least a 1/2HP,
  3. Cartridge filter, one that is for a spa or small above ground pool, and
  4. Chlorine generator, such as a Pentair Intellichlor IC40.

You will also need PVC pipes and fitting, and wiring to connect the pump motor and chlorine generator power supply to your electrical service. This set-up will require about 10 amps, depending on the circulation pump you select. The setup is relatively straight forward, if one has a basic understanding of plumbing and electrical. The components are assembled and installed similarly to a pool or spa setup. The tank needs to be plumbed into, with at least 1¼-inch PVC pipes, but 1½-inch pipes work better. Wall return fittings, for vinyl liner pools, work well for this. NO METAL FITTINGS! The bottom must be used as the suction and the higher line the return. Run the suction line to the suction port, on the pump. Then run a line from the pressure port of the pump to the cartridge filter. Even though the water that is put into the tank should be filtered to remove any debris, the cartridge filter is a precaution against the generator cell becoming clogged. After the filter, run a 1½” pipe, at least two straight feet, into the cell. After the cell, run another two straight feet of 1½” pipe back to the tank return point. Install a Tee-fitting, with a PVC ball valve, at a convenient point, low in the system to drain your hypochlorite solution into containers. The PVC ball valve should be installed at the suction and return points on the tank, so that service can be done on the equipment without needing to drain the entire tank.

Using your mini-chlorine factory.

When the water tank is filled, add the salt through a port in the top of the tank. Quality water softener salt works well. The cell will indicate when the salt level is at 3,400ppm. This is 1/10th the salinity of sea water. At this point, you simply prime the pump and make sure your valves, on the suction and return lines, are open so that you don’t dead head the pump. You need to know the concentration levels of the solution. I advise against going above 50ppm. It is easier to handle and it is unlikely that one would need a couple hundred gallons of bleach strength Sodium Hypochlorite. It is unnecessary to make more than one needs for a given period of time. At 50ppm, one gallon would disinfect 50 gallons of water at the 1.0ppm free chlorine level. So, a 200 gallon batch would disinfect 10,000 gallons. Keep in mind that these chlorine generators are designed to keep 40,000 gallon swimming pools chlorinated at 1.0 ppm or more 24-7-365. It is important to note that according to the CDC, Giardia and Cryptosporidium are highly tolerant against all forms of chlorination because they exist in a cyst or oocyst form while in the water. The CDC recommends ceramic filtration to remove these pathogens.


Testing the free chlorine level of your drinking water is of the utmost importance. The CDC recommends a free chlorine level of .5 to 1.0, to properly disinfect drinking water. The OTO and DPD reagents, that are commonly used to test chlorine in water, also suffer from the same problem of limited shelf life. The solution is to use an Oxidation Reduction Potential (ORP) meter. ORP meters measure the oxidizing properties of the chlorine sanitation level in water, by electrical current. Readings are generally in millivolts (mV). There are several ORP meters available, ranging from around $35 to $350. Get a quality meter that uses AA or AAA batteries that can be recharged. ORP meters are great preps because they can be stored indefinitely in an EMP-proof container and put into service when needed. All the components needed to make a mini-chlorine factory can be safely stored indefinitely, ready for the day they are needed. That can NOT be said for Calcium Hypochlorite.

The advantages of having one’s own hypochlorite generator are:

  1. It uses salt to generate chlorine, and salt can be stored indefinitely.
  2. Properly stored electrical components can also be stored indefinitely.
  3. It will produce full-potency sodium hypochlorite on demand.
  4. You would have your own hypochlorite factory for fun and profit when the SHTF.

The only long-term way to have chlorination, as a water sanitation option, is with a chlorine generator and a stockpile of inexpensive salt. I am surprised that more preppers are not aware of the potential uses of chlorine generators. I hope that I have been able to shed some light on this subject. Thank you and God bless.