How to Purify Water Using Iodine Tincture




About: I like sleeping far too much for my own good.

When you're in the wilderness, you need clean water to drink -- but water sources in the wilderness can carry bacteria such as giardia. You don't want giardia, trust me, and trying to carry a few jugs of Poland Spring would be extremely heavy and inefficient. Luckily, there are a number of ways to purify water, and one of the simplest, cheapest, and most effective ways is to use iodine tincture.

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Step 1: Supplies

To complete this task, you'll need the following:

--Water bottle: A Nalgene (what I use here) or a metal water bottle will work best, but all you really need is any container that will hold water.

--Iodine Tincture Solution: You want Iodine Tincture with 2% Iodine and about 47% alcohol. Bottles of this solution should be available at your local drugstore and a 2 oz. bottle is usually $3 or less.

--An eyedropper: Counting the number of drops is the easiest way to keep track of how much you're using.

--A good water source: This can be a lake, a river, a stream, etc. If you have a choice of water sources, consider these two tips:

Clear water is better than cloudy water.
Flowing water is better than still water.

Remember, though, that even if the water looks extremely pure and clean, it should still be purified before drinking. Looks can be deceiving!

Step 2: Fill Your Bottle

After finding a water source, you need to fill your bottle with water. To do this, position yourself close to the water source and tilt the bottle under the water. You want to collect water from near the surface, so don't just immerse the whole bottle in the water. Let the bottle fill up and remove it.

Examine your bottle of water to make sure there are not too many floating particles (called "floaties" in scientific terms). A couple of small floaties are fine, but too many large floaties can be dangerous. If this happens, you need to try filling up again. A way to solve this problem is to cover the mouth of the bottle with a bandanna or thin cloth that will allow water into the bottle but keep floaties out.

Step 3: Add the Iodine Tincture

Dip your eyedropper into the iodine tincture and squeeze up some of the liquid. Carefully position the eyedropper over the mouth of the bottle and add 5-10 drops per 32 fluid ounces (about 1 liter) of water. The exact number of drops is a personal choice (I can't make this decision for you) depending on the following factors:

The water source: if your source is a lake or some other still body of water, you want to add closer to 10 drops; if the source is flowing, you can add fewer.
The clarity of the water: you should add closer to 10 drops if the water is cloudy.
Your own aversion to the taste of iodine: some people hate the taste of iodine (it is a little bitter, and you will notice the taste in your purified water). If this is the case, you might want to add closer to 5 drops.

Personally, I'm a fan of 8 drops. If you are filling up a bottle or container that is not 32 fl. oz. or 1 liter, change your measurements accordingly. A 2 liter bottle will require twice the number of drops.

Step 4: Wait 5 Minutes

After adding the iodine, you need to wait 5 minutes before you can continue. You can go for a quick hike, admire nature, play a game, or think up an idea for your next Instructable.

Step 5: Thread the Bottle

After five minutes, you need to purify the mouth and rim of the bottle (which touched the original water source and which will touch your mouth). To do this, you need to "thread" the bottle. Turn the bottle upside down and slowly unscrew the top until you can see a ring of water appear around the inner rim. Once you see that ring of water, you know that the water with the iodine has touched the mouth of the bottle and disinfected it. Screw the top back on and flip the bottle right-side up.

A little water will probably leak out while threading, and that's not bad--it just ensures that you've fully threaded.

Step 6: Wait 30 Minutes, Then Enjoy!

The iodine needs time to completely purify the water. You need to wait 30 minutes before you can drink the water--plenty of time to finalize that idea for an Instructable.

After you have waited 30 minutes, your water is purified for drinking. Revel in the cool, clean taste of your iodine-infused water while you enjoy your wilderness adventure.

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250 Discussions


Tip 4 months ago

Ha! I actually love using iodine and actually have come to enjoy the taste!!
However, everything about this post is wrong :)

Filling your bottle: You want to fill under the water surface. Most debris is suspended at the surface. Instead open the bottle under the surface and close the bottle underwater
Using Iodine: Tincture... this is so difficult. Use potable aqua iodine. Simply follow the directions on the back. I typically dissolve for 20min before purifying the threads of the bottle
---pro tip: note different amounts of iodine are typically required depending on the source water temp and conditions.
---iodine should be apart of any backcountry first aid. also great for sterilizing wounds.

3 replies

Reply 4 weeks ago

Actually, most of the info in the article is correct - "everything about this post is wrong" is a great exaggeration and a bit harsh.
Most debris sink to the bottom. Filling your bottle "near the surface" (not AT the surface) is good advice for several reasons: So you don't stir up the debris on the bottom. Also, the water is warmer near the surface. One important thing the post did not mention was water temperature. Iodine is far more effective in warmer water - colder water (under 50°F) should be treated with closer to 10 drops.
There is nothing difficult about counting out and releasing 5 to 10 drops into a bottle of water. No need to worry about when the tablets dissolve. Tincture is far cheaper than your tablets. Also, iodine tincture is far more useful and practical than tablets when it comes to sterilizing wounds.


Reply 16 days ago

Hi Curthal. One thing in your message I take issue with... you note that colder water should be treated with more tincture? is that because tincture is more effective at warm temperatures?

When using iodine more is necessary at higher temperatures because anything growing in the water is more active and in greater abundance at higher temperature (shallower, still) water.

Lot of miss information out there... don't want to add to it!


Reply 15 days ago

I agree, there is a lot of misinformation out there and one should be careful not to add to it. With that said, I can't tell if you are being purposefully ironic by stating the exact opposite of the truth (providing misinformation) before ending your post with a statement warning against providing misinformation.

This is the correct information, supported by endless published research:
When using iodine, MORE is necessary at LOWER water temperatures.

I do not post comments lightly. Before posting, I am as sure as I can be about the validity of my information - I do my research as well, just to be sure. It is a simple thing that you could do yourself (preferably before posting).

Google "water temperature effect on iodine purification." You will find numerous solid sources that support what I have said. A US Army technical paper on iodine disinfection and water purification puts it succinctly: "Cold water temperatures slow disinfection and must be compensated for by longer contact time or higher concentration to achieve comparable disinfection at warmer water temperatures"


4 months ago

Will that be effective against chemical pollution? Say a can of pesticide was thrown in the creek and the water all nice and clear rolls beautifully. Would the iodine neutralize the pesticide ?

1 reply

Reply 4 weeks ago

Definitely not. Iodine does not remove or neutralize chemical toxins. Iodine simply kills microorganisms (protazoa, bacteria, viruses) so they can't infect you when ingested, as they can only make you sick if they are living when ingested. Non-living contaminants/poisons such as chemical toxins (pesticides, pharmaceuticals, acid rain) and heavy metals are not affected by iodine. Adding iodine to water contaminated by chemical toxins actually makes the water more dangerous - effectively adding an additional potentially dangerous toxin to the water. For, Iodine is also toxic to the human body if not used very sparingly and temporarily.
Only by properly distilling or filtering (with certain activated carbon filters), can chemical toxins be removed from contaminated water.


1 year ago

I love the idea of using iodine instead of chlorine. Our diets are deficient in iodine (unless you eat a lot of seafood).

If you don't like the smell of the iodine (which most people perceive as a taste), just crush a Vitamin C tablet and add to the water, reseal the bottle, and give it a shake. The color, smell and taste will all be gone! The iodine is still in there but now it's bound to the Vitamin C and you won't notice it.

Nice Instructible!!

1 reply

Reply 4 months ago

Just make sure you add the vitamin c tablet after giving the iodine the 30 min or so to work. I'm assuming that once the iodine has reacted with the vitamin c it will no longer be effective against bacteria etc as it not reactive

Nice tip, one that will help a lot of people I'm sure


4 months ago

Instead of using any kind of chemical substances in my drinking water as we did in the past with chlorine tablets (and sodium thiosulfate (known from developing fotos in the past) afterwards to make it smell less) I prefer using my small hiking filter that weighs 500 grams and keeps in its ceramic filter floating particles such as bacteria up from 2 microns. For filtering several chemical substances such as smelling stuff in the water I'ld recommend you using a filter that combines activated charcoal and ceramics. These filters are available in many sizes and prizes. And never take the water from streams below pastures!


4 months ago

There are several comments below warning of the danger of tincture being poisonous. I am not trying to be a smart alec but it begs the question: Aren't chlorine and particularly fluoride poisonous also? In fact, it would be interesting to see an Instructable about how to remove fluoride from drinhing water.


2 years ago

Me? I'm doing charcoal filters ONLY!! KISS

1 reply

9 years ago on Step 6

tincture is poisonous, Lugols solution is not. Use Lugols. All of the other halogens, flourine, chlorine, and bromine are also poisonous and replace iodine (which is a necessary nutrient) in the body.

7 replies

Reply 8 years ago on Introduction

I agree. You may want to simply change Iodine Tincture Solution to 2.2% Lugol's solution. Otherwise, you may have someone who is deathly afraid of Iodine, flag your post and then keep posting over and over about how your instructable "may" kill someone or "may" cause monkeys to fly out of their butt.

Unless you have a very rare case of being allergic to Iodine, Lugol's is not only safe, but actually good for you when taken is reasonable amounts.

Using Lugol's is much healthier for you than chlorine is.

""For many years physicians used potassium iodide in doses starting at 1.5 to 3 gm and up to more than 10 GRAMS (not milligrams) a day, on and off, to treat bronchial asthma and chronic obstructive pulmonary disease with good results and surprisingly few side effects."" !!!

Please read the article yourself:

I sure am glad that the "deadly poisonous, and super duper highly toxic iodine" fear mongering is over now.

dude's before stating that something is poisonous how bout actually looking to see if it is.

Now i AM a chemist and looking up the MSDS it states the ld50 of Lugol's iodine AND tincture of iodine is 30 mg/kg! Why?? Because both Lugol's and tincture are just different ways of solubilising elemental iodine, which is poisonous but your body can hack a bit of it, same as chlorine.

Elemental iodine is very insoluble in water so it needs something to help it dissolve. Lugol's solutions uses a salt "KBr", while tincture uses ethanol and a lot less KBr, or NaBr. Your body can hack alot more ethanol than it can iodine.

This method that has been shown is technically sound, Just don't use two much iodine so you don't kill your liver.


Reply 2 years ago

It can not process industrial ethanol man!!!!!!! it will kill you


Reply 2 years ago

What do mean by "industrial ethanol"? Perhaps you are thinking of denatured alcohol? While denatured alcohol may be poisonous (depending on how it was denatured), it is very likely that the the ethanol in a tincture of iodine is NOT denatured. I say likely only because I don't know this for a fact but you can look at the ingredients on the label. If it says 5% ethanol it is not denatured. If it says 5% denatured alcohol it is. Furthermore, a few drops of 5% ethanol in a half gallon of water is totally safe, even for those who never drink.


Reply 2 years ago

I qt of cheap will kill most anything in the qt of water. More fun than iodine

Bleach also works. Prepper school:

Place the water (filtered, if necessary) in a clean container. You can use coffee filters, or towels/shirts to filter the water prior to treating it with bleach. Add the amount of bleach according to the table below. Mix thoroughly and allow the water to stand for at least 30 minutes before using (60 minutes if the water is cloudy or very cold). Treating Water with a 5-6 Percent Liquid Chlorine Bleach Solution Volume of Water Bleach Solution to Add (Clear water) Bleach Solution to Add (Cloudy, Very Cold) 1 quart/1 liter 3 drops 5 drops 1/2 gallon/2 quarts/2 liters 5 drops 10 drops 1 gallon 1/8 teaspoon 1/4 teaspoon 5 gallons 1/2 teaspoon 1 teaspoon 10 gallons 1 teaspoon 2 teaspoons Purifying water with bleach is safe if you follow the proper guidelines and use the correct type of bleach. Only use Calcium Hypochlorite bleach, and avoid using bleaches that contain perfumes, clarifiers, dyes and other additives. Be sure to read the ingredients on the label.

Copyright © Read more at:

If you have a choice between Lugol's formula and some xyz brand pushing tainted Iodine, what are you reaching for? and yes, Alcohol is POISON to the body - elementary knowledge. So what if everyone chooses it to subdue their lives - what's that old folk name they call it .. choose your poison..referring to ALCOHOL. Do you know the function of mixing Iodine with Alcohol? Again, why use inferior when you can choose the best. And the body does not 'hack' iodine, it utilizes it. You are a bit mixed up with your logic.

Alcohol is less toxic than iodine. Look up the lethal doses. Sounds like you are on a bit of an iodine mission here. Just because you take iodine every day below the level of toxicity doesn't necessarily mean it is good for you or anybody else. The body does need a very very small amount, micrograms per day, but not milligrams per day. And no, I am not a troll for the pharmaceutical industry. (That any such person would be following this tread so somewhat laughable.)