Note: This post has a correction. Scroll to the bottom to view.
Regarding the recent chemical spill preventing over 300,000 people in West Virginia from using their water, I wrote on Facebook about water purification, “unfortunately, I know of no improvisational method that removes chemicals.”
Some commenters suggested distilling could in fact do just that. Others wondered about activated charcoal.
Excellent suggestions, especially in a situation where there’s no expert alternative. What I should have written was, “I know of no method that reliably moves all chemicals.”
Of course, by far the best option for the people affected by this West Virginia spill is to use already stored water or water brought in by trucks, but what if their only option were to drink the contaminated water or die of thirst? Does either of these methods work to remove chemicals from drinking water? Just as important: Do they work to remove the specific chemical spilled, 4-methylcyclohexane methanol (MCHM)?
Note: Check with local water or city authorities after any chemical spill before trusting any purification or filtration method. As always, this post is for general information and not meant to be your only source.
Distillation to Remove Chemicals From Water
What you need to know to be sure distilling will work: That the chemical’s boiling point is sufficiently above water’s boiling point.
Necessary supplies: There are many setups you can use to do this—from complicated, like an old-timey whiskey still, to a couple of pots with a heat source, as shown in this video by MomPrepares.com.
Will distilling remove MCHM from drinking water? Apparently so. The boiling point of MCHM is 180 C, according to Eastman, the company behind the West Virginia chemical spill. Water’s boiling point is 100 C.
Overall, distillation is the best method to ensure the purest drinking water. And because it works so well in removing all minerals, good and bad, there is debate about whether this may have its own health dangers if it’s your only source for drinking and used for lengthy periods.
The basic premise is you boil the water and catch the steam, as it condenses back as a much purer liquid, in a separate container. Minerals and any water-insoluble contaminants will remain behind in the original container. The chemicals that have a boiling point higher than water will not turn to steam and will remain in the original container as well.
Because distillation requires boiling for a while, it kills bacteria, viruses, and parasites. If done properly, distillation like this can remove about 99 percent or so of pollutants, but it can’t be counted on to remove chemicals that have a boiling point around or below water. These products will turn to steam the same as the water and end up in the second “purified” container. Examples include toluene, benzene, some pesticides, and others.
You can find more information about chemicals that are and aren’t removed, and about distilling drinking water in general, here.
Activated Charcoal to Remove Chemicals From Water
What you need to know to be sure this will work: That the chemical is a type that activated charcoal can absorb.
Necessary supplies: Basically, you need enough activated charcoal (which is not the same as plain charcoal). It comes packaged in a variety of systems, including portable water bottles and attachable faucet filters.
Do we know whether activated charcoal will work for MCHM? Unclear. Though Eastman is reportedly using powdered activated charcoal in the cleanup, I can find no guidance on home use for this chemical. I’ve contacted various experts and will update this post if I hear back. (I’ll also email subscribers directly with their answer.) Update: Scroll down for a response from Berkey Filters.
Activated charcoal, also called activated carbon, has been treated in such a way as to open up tiny pores and increase the surface area so much more liquid comes in contact with the charcoal carbon. The carbon reacts with the pollutants, attaching them to the charcoal.
Although this method removes chemicals, it does not kill bacteria, viruses, or parasites, so you’ll need to combine it with one of the methods that disinfects. I have a post on some of those here.
Some water filters you can buy combine activated charcoal and the micropore method for removing germs into one container. As I discuss in my book Living Ready Pocket Manual: First Aid, the micropore method, or microfiltration, “involves a water filter with holes too small to see—no bigger than 1 micron in diameter. Most protozoa and bacteria are larger than 1 micron, which is why the filter is able to remove them.” I go into a little more detail in the book, but hopefully you get the idea.
After many uses the activated charcoal gets its fill and is no longer useful, so you’ll have to replace it. How often is a guess and related to how much water you filter and how contaminated it is.
You can find more information about using activated charcoal for drinking water, along with examples of the chemicals it doesn’t work on, here.
So as you can see, while distillation or combining activated charcoal with a disinfection method isn’t perfect, it’s the best we have in austere situations.
What about you? What’s your favorite method to remove chemicals from drinking water? Please add any constructive comments, also, to what I may have left out.
Photo: As seen at the American Revolutionary War reenactment, Cantigny Park, Weaton, IL. Courtesy Flickr/Lyle58. Licensed via Creative Commons Attribution-NonCommercial 2.0 Generic (CCBY-NC 2.0). Cropped.
Updates to This Post
Correction: This post originally said distilling would not work on MCHM. Instead, it apparently will. (However, always check with your local water or city authorities after any chemical spill before trusting any purification or filtration method.) A box in this post also stated that for distilling to work, the chemical’s boiling point must be below water’s. It should have said the boiling point must be above water’s. I apologize for the errors.
Addition: We asked a number of water experts, both government and private, whether activated charcoal for home use would remove MCHM from drinking water. The only one to give us an answer so far is Berkey Filters, makers of some popular home and portable purification systems. (The United States Environmental Protection Agency did promptly respond to our inquiry but didn’t provide an answer. They asked whether we’d contacted the West Virginia state or water department about this.)
Berkey says its systems haven’t been tested with MCHM, so they don’t know whether they’d work. They suggest that in a situation like the one in West Virginia people consider purifying rainwater or lake water if it hasn’t been contaminated with the chemical. Their full response is below.
Note: Berkey uses what they call Black Berkey Purification Elements. They don’t say whether the “elements” include activated charcoal. A customer service representative told us they’re “proprietary, but the manufacturer informs us that they are a carbon-composite matrix.”
Berkey Filter’s Response:
The Black Berkey Purification Elements are able to filter out a large number of chemical contaminants, but they have not been specifically tested against 4-methylcyclohexane methanol. The reason is that this chemical was not listed by the EPA as a chemical to test water filters for. We have placed a link on our site to a PDF file that lists all of the volatile organic chemicals the filters have been tested against. You can find that link here: http://www.berkeyfilters.com/berkey-answers/performance/filtration-specifications/. It is in the section of Volatile Organic Compounds near the bottom of the page.
In general terms our filters are designed to be used in emergency situations and are actually classified as water purification elements as opposed to water filters. One of the strategies that can be used in a situation like that in West Virginia, where the element’s performance against an untested chemical is not known, is to use the filters to purify water from a source that is known not to be contaminated with that chemical. Examples would be rain water or water from a lake that is not connected to the contaminated river system. The filters will remove the biological contaminants and sediment from that water and provide a safe alternate source of drinking water. The only type of water we do not recommend using in the filters is seawater as the salt will greatly reduce their lifespan.