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September 4, 2005

Arranging for a supply of water

As the situation in New Orleans makes clear, protecting your supply of drinking water is a critically important element of disaster recovery. You can survive for weeks without water, but only days (the rule of thumb is three) without water. However, with a little planning, it's easy to ensure your supply under most conditions.

Ensuring you have water
The most surefire approach is simply to stockpile water. Basically, you take a bunch of food grade plastic water jugs/bottles/cans and pour water into them. You can easily find 5-7 gallon containers of this type at camping stores. How much water you'll need depends on your habits, climate, etc., but you should assume at least a minimum of a gallon per person per day, and probably more like two. You'll also want to add some sort of preserver to block bacterial growth. Bleach works well. This keeps the water good for about 5 years at which point you have to drain and refill the containers. You can also buy portable long-lifetime water. Aquablox is a well-known brand in a convenient package. It's probably too expensive to go this route for bulk storage, but it's convenient for portable applications.

The big advantage of actually storing water is that it guarantees your supply. The big disadvantage is that it requires actually storing the water, so it clutters up your garage and however much you store is all you've got. Also, if your house/garage/etc. is damaged you may not be able to get at your stash. Still, it's not a bad precaution.

Decontaminating water
The good news is that the problem usually isn't actually a lack of water, it's just that what water there is is contaminated.

There are five basic kinds of contamination to be concerned about:

As this Slate article points out, the short term risk of chemical contamination is fairly low, though you wouldn't want to drink chemically contaminated water in the long term. However, in most developed countries it's safe to assume--or at least it seemed so until recently--that water supplies will be restored within a few weeks, so this probably isn't a serious problem.

Particulates, bacteria, parasites, and viruses are a standard problem in camping and backpacking situations because a lot of wilderness water sources are contaminated, so there's a set of standard solutions: chemical purification, uv purification and water filters. Each of these has advantages. Chemical purification is the cheapest and most portable. You can buy purification tablets or drops from camping stores or just use bleach. The big advantage of the camping preparations over bleach is that your water doesn't end up tasting and smelling funny. The big advantage of chemical purification is that it kills bacteria, protozoans and viruses. The disadvantage is that it's slow--you cayn have to wait up to four hours for the water to be safe to drink. Also, it doesn't do anything to remove dirt, silt, etc. and there are concerns about the level of purification you get if your water is contaminated with particulates. You can also get electrical salt-based purifiers. These use basically the same chemistry as chemical purification (at least some of the chemical methods) except that an electrical current is used to create the chlorine dioxide. These have a higher fixed cost but only require salt rather than specialized chemicals.

A newer option is UV purifiers. This is just a handheld version of the kind of UV-based purification that is common in municipal water treatment. UV kills bacteria, parasites, and viruses, and is much faster than chemicals, but still doesn't work well on cloudy water. It also chews through batteries really fast, which doesn't make it great for emergency use.

Probably the best technique in this situation is water filtration. There are a large variety of hand-pumped water filters available for around $50-$100. I use a Katadyn Hiker for backpacking, but all the major brands work well. Typical weights for small units are under a pound, and even a small unit can provide plenty of water for a medium-sized group: water production rates are about a liter a minute with fairly easy pumping action. The big advantage of these filters is that they will remove particulates as well as bacteria and viruses. You can also get them with activated charcoal filters that will help remove chemical contamination--though it's not clear how good a job these really do in this kind of situation. The two big problems with filters are that they don't remove viruses and that they clog, especially if you use them with really particulate-heavy water. I suspect that the virus issue isn't that important but the clogging is. You can get prefilters that will help but it's best to let as much sediment settle out of the water as you can as well. Note: I've never actually had a filter clog on me.

It's probably best to have both a filter and some method of chemical purification on hand. This gives you a backup in case your filter clogs and you can't clean it. You can also use your chemical purification method on the water you filter to kill viruses.

Desalinating Water
If you live in a coastal region, there's a good chance you'll have access to salt water. You can't drink salt water and unfortunately, water filters don't do anything to remove the salt. You can buy desalination units, even handheld ones, but they're expensive ($500-$2000), slow, and require enormous energy input to operate. Typical water production rates are between one and five liters an hour.

A desalinator is probably only really worth having if you think that there's a really good chance that salt water will be available but that fresh won't (like in a marine environment) or if you expect to have some way of powering it (for instance, off your car, since many of these units take 12 volt input).

Acknowledgement: Thanks to Kevin Dick for talking over these issues with me.

Posted by ekr at September 4, 2005 6:17 PM | Filed under:

Comments

What about buying gallon, or multi-gallon jugs of distilled or spring water, and storing those? It seems simpler to plan for a week or so with stored water than to buy purification gear.

Posted by: Adam at September 4, 2005 9:06 PM

Well, I do suggest storing water as one alternative, though it has disadvantages. However, it's probably better to get long-life water like aquablox. I'm not sure if store bought distilled water has that great a lifespan, so you'd have to rotate your stock.

Posted by: EKR at September 4, 2005 9:08 PM

Note that the white store-bought PETE and HDPE water containers will only last about a year or so before they crack and leak. (she said, former owner of four stored five gallon jugs of water, now the owner of a completely ruined hardwood pantry floor). Make sure you rotate your containers or at least check them.

Posted by: lauralemay at September 5, 2005 10:18 AM

What about the smaller-size clear water bottles? I'd assumed they lasted a very long time--am I mistaken? (They also have the advantage that they can be obtained for free, by scavenging for leftovers at meetings, conferences, etc.)

Posted by: Dan Simon at September 5, 2005 10:44 AM

I've had containers similar to these:

http://beprepared.com/product.asp?pn=WS%20B080

for 7 years (I've rotated the water twice). No cracking or leaking. Be sure they're stored outside of direct sunlight because UV will eventually break them down

At $13 for a 5 gal container, it's hard to see why you'd want to scavenge 500ml water bottles that aren't nearly as sturdy and then go through the hassle of individually cleaning and filling them. Also, I can't find anyone that recommends this procedure, leading me to believe that they may not be suitable for this purpose. Certainly, everyone recommends completely opaque containers because exposure to light decreases water shelf life.

Posted by: Kevin Dick at September 5, 2005 12:46 PM

I was thinking of full, sealed water bottles--no cleaning and filling required. How long can they be expected to last, if stored in a dark closet? Usually, they have two- or three-year expiration dates, but I always assumed that that was because of the plasticky flavor that eventually leaches into the water, not because the container (or the water itself) ceases to be a reliable emergency supply. Is that a mistake?

Posted by: Dan Simon at September 5, 2005 2:46 PM

Oh, untouched bottles. The expiration dates on these are probably accurate. I've read that unpreserved water lasts 6 to 12 months. Presumably, bottled water is bottled under somewhat more sterile conditions than filling a jug from a tap. Avoiding exposure to light and heat will always increase the shelf life. If you go through a lot of bottled water anyway and are anal enough to use a FIFO queue, maintaining a large inventory of bottled water is probably a fine idea.

Posted by: Kevin Dick at September 5, 2005 2:51 PM

When living in the path of hurricanes, I adopted this procedure: just before the hurricane we would upgrade our "wall of water" which was a section stacked with boxes of drinking water, 12 x 1.5l per box. Each box was about $10, so the wall would cost $100-$200 to upgrade.

Then we'd just drink our way through it. As drinking bottled water was preferrable anyway, this wasn't an issue, and was far more convenient than any other methods suggested.

But there is another aspect of water that was harder to understand because the local disaster instructions (and what is written elsewhere) aren't clear. What they say is that you should fill the bath with water and any old 5 gallon drums.

It wasn't until after my second hurricane that I figured out why this was so - toilets! When the power goes out, the pumps go out, and the toilets don't get a refill after flushing. So you need lots of non-drinking water to do a flush. (Which oddly isn't a problem in a hurricane as there is usually lots of mopping up to do during the storm but as power might be out for up to 6 weeks or so, this is an issue...)

After we discovered that, hurricanes were ridden out in much more civilised conditions :-)

Posted by: Iang at September 6, 2005 6:28 AM

Out here in earthquake country, such a wall of water is not a very good idea as it's likely to crush or be crushed. It's also harder to evacuate quickly. A reasonably fit adult can move 20-30 gallons worth of 5 gal containers to a car in less than 2 minutes (10 gal per trip).

Posted by: Kevin Dick at September 6, 2005 9:29 AM

thanks for the tip on the Katadyn Hiker, btw -- having spent a while backpacking with just iodine, I'm now quite willing to spend the $60 to buy a filter. Iodine is quite unpleasant to use for *all* your daily hydration needs.

Posted by: Justin Mason at September 7, 2005 4:38 PM

Justin:

You might consider the Hiker Pro. The connectors look a little better.

Also, iodine is about the worst chemical purification technique. I hear that the chlorine dioxide ones (aquamira and Micropur MP-1s) taste a lot better.

Posted by: EKR at September 7, 2005 4:52 PM

In this article you have a very bad typo - it says you can survive for weeks without water????

September 04, 2005
Arranging for a supply of water
As the situation in New Orleans makes clear, protecting your supply of drinking water is a critically important element of disaster recovery. You can survive for weeks without water, but only days (the rule of thumb is three) without water. However, with a little planning, it's easy to ensure your supply under most conditions.

Posted by: Anne Mowery at September 13, 2005 6:51 AM