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Water Filtration for Emergency Preparedness

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Water: it can save us or sicken us. When our water supply is compromised, knowledge and preparation make all the difference.

By Posted Aug 14, 2014

It’s a topic many of us would rather avoid. With climate change news worsening, and dire speculations increasingly credible, it’s natural to feel like changing the channel. Extreme weather events are popping up in all kinds of formerly peaceful areas. Big storms can render wells and public water supplies undrinkable, when runoff washes chemicals such as pesticides and solvents and even raw sewage from failed septic systems into aquifers. As if that weren’t enough, the threat of water contamination by oil spills, bioterrorism, or radioactive contamination haunt our fears.

Preparedness can help with the anxiety, though. We can sit down, walk ourselves through some worst-case-scenarios in our minds, and put together the necessary supplies to weather the storm (or whatever it is). Once our emergency kits are safely tucked away in a closet, garage, or basement — and once we’ve sat down and actually agreed on some plans with our loved ones — the monsters of “what if” have lost some of their terror. And the foundation of every disaster plan is water, because water is the foundation to our very survival. Safe water, that is.

Many a hurricane victim has faced the literal version of the proverb: water, water, everywhere, and not a drop to drink. Contaminated water can cause short-term life-threatening dehydration from vomiting and diarrhea, or long-term health problems due to chemical or bacterial toxins. North Americans take our exceptionally safe tap water for granted, but even here, communities can be taken by surprise by sudden “boil water advisories”, often the result of a broken water line causing possible influx of pathogens, or local flooding. Residents of Toledo were doubly confused this month, first by a warning of dangerous levels of microcystin, an algal toxin that can cause abnormal liver function among many other symptoms: don’t boil your water, residents were told. Boiling will only concentrate the toxins through evaporation. Days later, they were told to boil all water before drinking — only later was it clarified that the boil advisory was in response to a separate event (a broken water main with possible bacterial influx).

When it comes to water, what is “prepared”? Ideally, it’s a combination of more than one of the safety nets below. Depending on your personal situation and your region, some of these may be more do-able than others.

1. Bottled/stored water


We should all have a stash of safe water that needs no preparation. One gallon per person, per day is the rule — have enough for a minimum of three days. Store-bought bottles are simplest, as they are sealed and guaranteed drinkable through the expiry date (always keep track of that date and rotate your stock before it arrives). If you choose to store your own well or tap water, be aware it may need treatment (boiling or chemical) before drinking — some bacteria can survive even treated city water which over long stretches of time in enclosed spaces could multiply to unsafe levels. Rotate every 6 months to be safe. For long-term storage, the EPA recommends 4-ppm chlorine: you can achieve this, if desired, with bleach and swimming pool test-strips. Sterilize and seal containers. And in the short-term, remember to fill up your bathtub and large cooking pots at the first extreme weather warning. Store bottled water stocks are often the first to sell out during storm warnings. Filtering stored water before use will improve both the taste and the purity.

2. Emergency filtration systems


A good filter is essential — some of the best emergency filters were developed to save lives in developing countries where unsafe water is an everyday reality. Unfortunately, supermarket charcoal filter pitchers like Brita or Pur won’t help with many pathogens or chemical contaminants. There are a million water filters out there, and the search can be dizzying. For emergencies, we’ll narrow it down.

The best preparedness filters need no electricity or running water to operate; are tested for effectiveness on pathogens and a wide range of contaminants down to .2 microns; will filter a quantity sufficient for your family’s needs. Unless you want to join the pioneers who are field-testing improvised low-tech DIY filter systems using peat moss, sand, and charcoal, you’ll probably be shopping online for the right filter. Here are our favorites.


Lifestraw is in a category by itself for portability (it weighs 2 ounces), compact storage, effectiveness and affordability. If you ever need to evacuate, you’ll thank yourself for the foresight of buying a Lifestraw for your evacuation kit. Time magazine declared this product “Best Invention of the Year”, and the company is committed to its service mission: for each one purchased in North America, a child in Africa gets safe drinking water for an entire school year. Simply use it like a straw, placing the flat end into the untreated water. Lifestraw is also a must for traveling to countries where you would normally resort to buying bottled water.

Lifestraw Family.

For those of us who live in a household of more than one, the Family version adds several features to the original, including increased filter capacity and storage, as well as enhanced filtration which will exclude even tiny viruses (filter has a pore size of .02 microns). This unit can provide you with 9-12 liters of incredibly clean water each hour.

Big Berkey.

The Berkey is an everyday fixture in many homes where water quality is a priority. It’s attractive and capacious as well as thorough. Its higher price will pay off if you’re shopping for a filter to enhance your drinking water today as well as in a crisis. The included “Black Berkey” purification elements give this countertop system its exceptional power to exclude viruses, bacteria, VOCs, pesticides, solvents, and a host of other unwanted elements which have unfortunately become common in surface water.

3. Boiling

The Red Cross actually recommends a combination of boiling for one minute, then treating with bleach. Other sources rely on boiling alone as sufficient, though some err on the side of caution, boiling for up to 10 minutes to be sure all pathogens are eliminated. First filter out any sediment or turbidity: simply pour through a coffee filter, paper towel, or clean t-shirt, changing the filter material whenever it begins to look dirty. Any particles in the water can provide a hiding place for bacteria, protecting them from the boiling water (this is the same reason you must always boil suspect water for the full time allotment before adding food for cooking). Pro: it’s simple, low-tech, and effective. Con: it requires fuel to achieve, which may be limited or unavailable in an emergency. If your stove requires electricity to operate, for instance, you should not make boiling fundamental to your water treatment plan.

4. Chemical disinfection

Bleach is the most common and universally-accepted chemical treatment for water. If you drink city tap water, chances are you’re already used to the smell and taste of chlorine disinfection! Every household should have a bottle of plain unscented bleach with no additives (5 to 6 percent sodium hypochlorite should be the only active ingredient). Have an eyedropper stored with the bleach: “one drop” is actually a scientifically standardized measurement unit, unlike “one teaspoon”. Prefilter the water as specified above. Use 16 drops per gallon of water. Stir and let stand for 30 minutes. Check for chlorine smell; if there is no detectable “swimming pool” aroma, add another 16 drops, stir, and wait another 30 minutes. If at this point there is no chlorine smell, the water may be too dirty for treatment, and should be discarded.

Some sources also recommend iodine tablets, or using liquid iodine from your medicine cabinet. Since iodine is not standardized as bleach often is, treatment quantities can vary. Be aware that sunlight can compromise iodine’s potency, and that some individuals have allergic reactions or health problems that may be impacted by iodine ingestion.


5. Distillation

If pathogens are your only problem, boiling or bleach treatment should take care of them. If, however, you know or suspect there may be additional contaminants (agricultural or industrial chemicals, heavy metals, or organic toxins), distillation achieves impressive purity from the foulest water. In some cases, a distilled product will surpass even the best filter in its thoroughness. Unfortunately, as a method it has some drawbacks. First, like boiling, it requires fuel — only more, and for a longer time. (In sunny climates, you can get around the fuel requirement by distilling in your solar oven!) The quantity of clean water produced is quite small and energy-intensive.

The Survival Still Water Purifier and Desalinator can make consistently pure water from any source in an emergency, even swimming pools, ponds, or seawater. It removes all contaminants including radioactive isotopes, toxic metals, and organic pathogens. This unit will produce pure water from the ocean or the murkiest pond with ease.

You can also experiment with making your own solar distiller for an added challenge. Or use your MacGuyver spirit to rig up a distiller on the fly: tie a cup to the handle of a large pot in such a way that the cup can hang right-side-up inside the lip of the pot. Fill the pot half-full with untreated water, making sure the cup does not dangle into the water. Boil for 10 minutes, then pour off whatever water has condensed into the cup. This will work in a pinch, but can be tricky to create and inefficient.

6. Rainwater catchment


Collecting your own rainwater is another useful practice to incorporate into your daily life: rainwater reduces overall household water needs, and is great for garden and landscape irrigation. In an emergency that keeps you at home for an extended period without running water, your rain barrels become a lifeline. If your system is kept clean and rotated, the resulting water can be consumed with only basic filtration. Unless local regulations prohibit rain barrels, many homeowners can install their own simple systems for up to 100 gallons of storage.

Choose a combination of emergency water options that feels right. Depending on the emergency, you may be advised to boil or disinfect your water, or alternatively not to drink the water at all, turning instead to your stored water supply or distillation. If someone in your household has a weakened immune system, plan to use a combination-treatment approach — boiling and/or chemical treatment followed by filtering, for example. For healthy individuals, a single situationally-appropriate treatment may suffice; keep in mind that no tap water is sterile, and trace quantities of bacteria below certain thresholds are considered safe by the EPA.

Each home sets up its emergency plan to match its members’ priorities, beliefs, and risk-tolerance. Apartment dwellers may have less storage space, making high-quality filtration even more important. A rural family with a large well or storage tanks may feel self-sufficient, but if forced to evacuate will need portable options.

Weigh your needs and options, but don’t procrastinate: disasters don’t happen on schedule.


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