Activated charcoal filter that can be used with standard water bottles?

Don't know of any charcoal filter that fits the bill. I had luck with a cheap, walgreens filter that i fitted onto my platypus.

I've "heard" that ascorbic acid (a form of vitamin c) neutralizes chlorine. It's fairly cheap and easy to get stuff. Will sour up your water a bit though. Since it's commonly used as a semi-natural preservative, it may even help to prevent microbial growth.

Derek,

You might be better off MYOG. I started a similar project a few years ago to use with household chlorine bleach drops instead of Aqua Mira. I came up with using activated charcoal inside a stainless mesh strainer that screws onto a Nalgene:

http://www.amazon.com/GSI-73020-Outdoors-H2JO-Percolator/dp/B000PGPGQC

You can buy activated charcoal at Petsmart in the aquarium section:

http://www.petsmart.com/featured-shops/marineland/marineland-black-diamond-carbon-zid36-1832740/cat-36-catid-800723

Put the AC in the percolator/strainer, screw that onto a Nalgene with bleach-treated water in it and then use a standard Nalgene lid on the strainer. After a bit, you could remove the strainer, put it in a ziploc (or some container) and put the standard lid back on. Hope that description makes sense.

I never completed this because I just use a Sawyer filter.

Bleach is alkaline. If you only add a little bleach, it'll only raise the ph a little. Adding ascorbic acid will make the ph more neutral.

But the chlorine is still there. I guess bleach + ascorbic acid will taste different, and if you like that taste better then you've accomplished something.

Would it be helpful to suggest a Steripen?

Some filters have an activated charcol element.

So I have to preface this with a disclaimer: I am not a chemist! But, I've done a lot of research about this, and I'm pretty sure that chlorine dioxide follows the same rules as chlorine and iodine: half the dose, double the contact time, and you have the same reduction of microbes. I'm not 100% sure, so I do half the dose and triple the contact time – I found some post where someone had inquired with Aqua Mira about it and was told that the relationship "wasn't linear", but it was implied that it was close to linear. I've also found some world health organization research that seems to imply it being totally linear.

But anyway, on to the practical applications – put half the drops in your water, treat for 2-3 times as long, and you've treated your water with less ill effects. I tend to get heartburn when I do a lot of full-dose aquamira, but when I do overnight low-dose filtering I don't have any problems.

This is more useful in the desert than in places that have a lot of water. I tend to camp near water sources if possible, so I will put in a very low dose of aqua mira (like 10 drops for a 6-liter dromedary bag) and treat water overnight. If I lived in a state with more water I would be very tempted to buy a steripen.

There are some studies that show that ascorbic acid will actually lessen chlorine. Not just a matter of ph, i don't think.

Bleach and chlorine are not the same thing. Bleach has chlorine, but in specific bonded forms, most commonly sodium hypochlorite. It's the sodium part that makes it more noticeably alkaline.

Steven gives some ideas for a MYOG GAC (granular activated carbon) filter. I've posted others over the years.

The other, broad approach is a tea bag of GAC. That could be an empty or recycled tea bag (some are made of a fine mesh clothe, maybe nylon), tea ball with fine openings (I.e. a wire mesh one) or, my favorite – the toe end of nylon stockings with enough length to tie a knot and loose enough to squeeze into and OUT OF your wide-mouth water bottle.

Put the GAC tea bag in AFTER the required contact time. It will get 90% of the chlorine pretty quickly and continue to remove chlorine – 99%, 99.9%, etc – as long as you leave it in.

Cleaning up toxic sites using pet shops, auto supplies, and Home Depot since 1988,

David

Good point Justin. And we just exceeded my limitied chemistry knowledge : )

Chlorine does exist as a gas, but I don't think adding ascorbic acid would cause chlorine gas to form.

Interesting idea David, thank you for sharing.

David,
Do you have any experience with how many liters of water a tea bag of GAC would "treat" and how quickly it can take the chlorine taste out?

Also, is there any GAC that is not food safe, or can I use anything for this sort of application?

Derek, chlorine has a high affinity for carbon (it's fast) and has a high "loading rate" (an ounce of carbon adsorbs more weight in chlorine than of most chemicals). I'm tempted to test it in the garage, but my guess is a tablespoon of GAC in a tea-bag-sized bag would significantly improve the taste in a minute or two of modest shaking or ten minutes of soaking with an occasional shake (hiking would provide plenty is sloshing about). A single "tea bag" would last for hundreds of liters of water.

Coconut-shell carbon rates higher for most compounds than coal-based. I can order special types in different sieve sizes, but that's in 1000-pound quantities. I suspect the pet store variety won't specify. Note that aquarium fish LIVE in water that has several times their body mass of GAC over in the filter. That's a great "wet test" that GAC doesn't release nasties (we use it because it adsorbs nasties) because fish die from very low levels of stuff (like chlorinated water) that we could drink many liters of).

> I guess bleach + ascorbic acid will taste different,

Jerry,

Vitamin C is an antioxidant. Chlorine and iodine are strong oxidizers. After the desired contact time, vitamin C will react with the halogen, canceling its odor and taste. You can buy it from Potable Aqua in their two-step scheme for improving taste. Or in the form of vitamin C tablets.

Derek: PM me if you want a few ounces. I keep some around and could drop it in the mail if you want to MYOG your own and see if it does what you want. I'd suggest starting with VERY small quantities – it is very effective and we are ULers, after all. -David

P.S. GAC is "activated" – it isn't just charcoal. It is has been heated above the boiling point of most organic compounds (hundreds of degrees in an oxygen-free environment) to drive them off (essentially boil them off) of the carbon surface. That clean, "activated" surface has high affinity for most organics and some inorganics, including chlorine.

One important thing to remember is to wait until the full treatment time is up before you do anything to the water to get rid of the taste.

I have found that the Aqua Mira taste, and I suspect stomach upset, is reduced significantly if your water container is left open for an hour or so.

Regarding ascorbic acid, you could add a pinch of any citrus flavored powder(Tang, instant lemonade, … They almost always contain ascorbic and citric acid.