Potassium Permanganate for Water Purification

Not actually Erin.
Picture by KJ Photography
& is used with permission. 

Water week concludes with a discussion about a chemical no prepper should ever be without: Condy's crystals, aka potassium permanganate. An entire series of articles could be written about the uses of this substance, as it can do so many things:

• disinfect wounds
• treat skin conditions like eczema, canker sores, and fungal infections
• start fires via chemical reaction when glycerin is added (video at link)
• dye snow or clothing as an emergency signal

But what we are interested in today is its ability to disinfect and purify water. 

Words of Caution

Before we begin, however, I need to make the following disclaimer:  Potassium permanganate can be harmful or fatal if used improperly. 

• Crystals, powders and concentrated solutions are caustic and can burn the skin. Wear gloves!
• Too much PotPerm can cause poisoning if ingested. Be aware of concentration in water!

What It Purifies

Not only does PotPerm disinfect water (it is used in the water treatment industry), it also removes microcystin toxins like the ones that compromised Toledo's water supply and inspired this week of articles: 

Potassium permanganate at 1 mg/L was found to achieve 95 percent removal of microcystin-LR at a starting concentration of 200 µg in 30 minutes, and higher permanganate doses achieved complete removal. 

However -- and this is important -- if you add PotPerm to water still contaminated by blue-green algae (such as in Toledo), the chemical reaction could result in the algae releasing more microcystin. 

Therefore, before you treat your water with potassium permanganate, it is recommended that you always, ALWAYS, filter your water (such as with the system David talked about on Wednesday). 

Procedure for Purification

First,  filter your water.  This will remove sediment, blue-green algae, and other nastiness you don't want to drink. 

Second, pour your water into a clear container. It needs to be clear so you that can judge PotPerm concentration from the coloration. If you do not have a clear container, use a one with a sufficiently large opening (like a canteen cup) so that you can see the coloration without having to look through a narrow bottleneck. 

Third, add PotPerm crystals to the water. Ideally, this is done with tweezers or a very small spoon, as it doesn't take much to disinfect water. The rule of thumb is 3-4 crystals per liter (roughly 1.06 quarts) of water.

Fourth, stir the water/shake the bottle to dissolve the PotPerm and disperse it completely into the water. Judge its coloration (below) to ensure you have the proper 1:10,000 (0.01%) solution. 

Finally, wait 2 hours before drinking. Keep the water in a dark place as PotPerm decomposes in sunlight. 

Color

http://chemistry-chemists.com/N6_2011/U7/ChemistryAndChemists_6_2011-U7-3.html

Above is a picture of several different concentrations of potassium permanganate in water. 

From left to right:

1. The leftmost bottle does not have enough PotPerm dissolved in it to make it safe to drink, unless it had already passed through a strong antibacterial filter. 
2. This is the darkest solution I would drink. Ideally you would want something halfway between #1 and #2, like the water in this picture:  

   

   http://www.practicalsurvivor.com/waterfiltration

3. This is too dark to drink, although it would make a good solution for treating wounds. If you needed to drink this, first add more water to dilute it. 
4. Use only for skin treatment. 
5. and 6. are too dark to be used as anything other than dye. 

A handy way of remembering this is "If it's pink, it's safe to drink." Aesthetic arguments over whether or not bottle #3 is pink or magenta are outside the scope of this article. My only recommendation is to choose pale pink over any other shade -- think steak, not Barbie or bubble gum. 

A Little Goes a Long Way

Remember, I said that 3-4 crystals per liter, or 1 part per 10,000 parts of water, is all that is necessary to achieve water purity:

• According to Cyanobacterial (Blue Green Algal) Toxins: A Resource Guide, one milligram per liter is enough to achieve 95% microcystin removal (each crystal is approximately 1 mg). 
• Per the United States EPA, a dose of 2.5 mg/L will completely kill bacteria. 
• Viruses can be killed, but dosages vary to be effective -- in some cases 50 mg/L are necessary for complete virus inactivation. This amount is close to toxic levels of PotPerm, however, and therefore I encourage you to get a filter with a high effectiveness against viruses if that is a concern 

As potassium permanganate is a salt, it can be stored for decades without losing potency, and since a little goes a long way it can be part of your preps for a long time to come.  You can buy it on Amazon in different volumes, depending on your needs. My only suggestion is that if you choose to include PotPerm in your bug-out or get-home bags, make sure it is tightly secured within a watertight container -- you don't want caustic salt spilling all over your emergency preps!

Here is a useful video for constructing a small, watertight container suitable for BOBs or GHBs.