Grid Down: Water Storage and Purification

Grid Down: Water Storage and Purification

Despite what they show on the heavily scripted survival reality shows, you can’t live long without water and you can’t magically extract all you’ll need from the ground using a solar still.

Water is at the top of the survival list for the simple fact that we humans must stay hydrated in order to survive. Whether you’re a triathlete, Green Beret or live in a desert cave, you can’t condition your body to go without this precious substance.

Having spoken with many survivors who were struck by disasters while living abroad in Japan, Thailand and India, as well as the debacle of Katrina, all of them recounted stories about the lack of fresh drinking water and mile-long resupply lines at aid stations. Most spoke about how they could handle the other priorities such as improvising shelter items from scavenged materials (clothes, blankets, furniture) and many banding together to provide medical assistance and share food. However, fresh water was scarce and dehydration endlessly tugged at their bodies and minds.



You can’t live long without this precious substance. Humans have lived weeks without food under survival conditions but without water, your shelf life is limited to a few days, possibly just hours if the heat is extreme.

Consider for a moment what would happen to residents in Phoenix or Las Vegas if there was a blackout lasting several weeks due to an incident that cripples the grid. During the summer, the temperature can spike past 115 degrees (F) in the afternoon. Working and living in a post-disaster setting like this would cause a person to consume two or more gallons of water per day. Life without water in these unforgiving city ovens can be limited to hours if the proper precautions and water planning aren’t in place.

The general rule I recommend, and that we have found useful at our house, is to have two gallons of potable water per person, per day on hand. This is just for consumption and cooking, not for dishwashing, laundry, livestock or the garden. For a family of four, this works out to eight gallons per day and 240 gallons a month. That’s a lot of water bottles to buy up in pallets, eh? I’m a real fan of layering your critical survival items so that your water is broken down into several storage systems from large to small.


Here’s what we’ve done. We have a 210-gallon water tanker that collects rainwater off our roof. This is the main vein for general use like dishwashing, animals and the garden along with just being an emergency back-up system.

The next step down are two, 55-gallon poly-barrels with accompanying hand-siphons. These blue barrels can be found at feed stores and some big-box pet stores for around $25. Some of these come from the commercial restaurant industry, so be sure to get the ones other than those used for storing garlic or olive oil—something I discovered the hard way.

Next, we have six of the blue seven-gallon cubes behind our shed (north-facing). These can be found in camping stores or at Walmart. I use these on my field courses, and they last for about eight months of punishment before the corners crack from the constant exposure to UV rays (at 7,000 feet where I live that’s a lot) and daily handling. If you’re storing these in your garage or basement out of the sunlight, then you should be fine. At the bare minimum, get two of these blue cubes and you will have 14 gallons of water, which will last one person seven days or a family of four for three days. Consider this a place to start and then you can build your water stores up from there.

Lastly, we have gallon containers in the form of iced tea bottles. We have a few of these on hand around the property and one in each vehicle, as this is a convenient size to tote around.

One of my students in New York City has 30 of these gallon jugs of water stowed in his small apartment (he’s a hardcore apple cider addict). At two gallons per day, he has enough for about two weeks. He cycles through these each month, which is what I recommend with all stored water.

We’ve used all of the previously mentioned water storage systems long-term and have never had any bacteria build-up as long as we are constantly rotating the water. Keeping containers out of the sun is helpful. Every three months after draining a water cube or the big barrels, I will completely bleach out the innards, rinse and refill. Bleach is a must-have item for maintaining your water barrels long-term and for water purification, as I’ll discuss next.


In a crisis, waterborne diseases are going to be a major concern so avoid the reality TV theatrics of gritting your teeth to strain out the big stuff and equip your home with some of the following low-tech items. These four methods of purifying water can be used for treating contaminated sources in both urban and wilderness settings.


Boiling kills both viruses and bacteria but does not remove chemicals such as fuel, lead or other toxins that may have leached into the city’s water lines when infrastructure damage occurs. According to a CDC researcher I spoke with, you need to boil water for only one minute to kill the microorganisms that are present. Actually, it’s 160 degrees (F) to be precise, but since we humans can’t tell when water is at that temperature on the stove or campfire, the CDC recommends the visual of the rolling boil to know you have exceeded the necessary temperature.


A SteriPen zaps the water with UV rays and kills both bacteria and viruses. Insert the tip of the pen into a liter of clear water and turn on the switch for 60 seconds. The drawback is that you need clear water to begin with. In murky or silty water, the UV rays won’t penetrate to the depth of the bottle and treatment will be incomplete. SteriPens are great for an urban survival home kit, but they do require four AA batteries, won’t function in extreme cold and are delicate. I keep mine in a bubble-wrap sheath when not in use. The company also makes a version that has a solar charger. I use a SteriPen when I travel internationally for treating water in hotels and remote villages. Again, it has to be clear water to begin with and the SteriPen only kills bacteria and viruses and does nothing to remove chemical contaminants.


This method for water purification is something that would be useful in an urban environment where chemical contamination is not an issue. SODIS was invented by a Swiss humanitarian group and it’s now used throughout third world countries to provide safe drinking water for thousands of people.

The method involves filling a clear plastic water bottle and then placing it in the sun for six hours. This allows the UV rays to kill the bacteria, viruses and critters. Very low-tech and simple and it will even work on a semi-cloudy day.

Some things to remember: it only works with clear PET plastic bottles; water on the cap and bottle threads won’t be purified and a straw is recommended to extract the water safely from the bottle when drinking. Like the SteriPen method, you also need clear water to begin with, otherwise the turbidity will prevent the UV rays from penetrating. Still, this would be a good method to file away for an urban setting as 1- and 2-liter bottles are plentiful. SODIS has its research and methods detailed on its website including information on how it can be used even in cloud-covered cities like Seattle. For further information, check out


You can use a modern hand pump filter like an MSR or Katadyn to treat water and remove any bacteria. These work best if you pre-filter the water through a coffee filter or bandanna. I like the MSR and use it on personal wilderness trips. The advantage with the MSR is that you can strip the unit apart and clean the (ceramic) filter. Most of the other models have pleated filters that must be replaced frequently. Some mechanical filters will also remove chemical contaminants.

Another excellent water filter system that’s been used for years in the self-reliance and homesteading community is made by Berkey. These are not intended as portable units for a bug-out kit but for the home. The Berkey filters come in six models and range in size from 1.5-gallon to 6-gallon models and the internal filters can be cleaned. Just keep in mind that these are gravity-fed systems so it’s not like turning on the tap but, hey, in a grid-down situation you will become time-rich anyway.


There are three chemical treatment methods available: bleach, iodine—in either tablet, crystal or tincture form—and chlorine dioxide.

Keep in mind that chemical treatment is similar to boiling water. It’s only going to kill viruses and bacteria and does nothing to neutralize other chemical toxins that may be present in an urban disaster when fuel, oil or other hazardous substances leach into the water table.

Bleach is my preferred method for an urban setting as it’s cheap, easy to use, kids can handle the taste compared to iodine, and it’s good for household sanitation. I have several friends who have hiked the Pacific Crest Trail over a five month period while using bleach for water purification on a daily basis.

On our field courses, we use six drops of plain bleach per quart of water. Make sure you use plain bleach as the scented variety has a detergent additive that will make you sick. One of my students, who is a chemist, recommends adding a few drops of food coloring into the bleach solution, so you can monitor its spread throughout the water being treated.

Iodine has been used for years by the military as well as the backpacking community. It can have a gag factor. The key with iodine treatment is to follow the manufacturer’s directions as company specs vary. I use the Potable Aqua brand which has 50 tablets per bottle and a shelf life of one year after it’s opened. Two tablets per quart of water is the recommended treatment. The only drawbacks: iodine is not good for pregnant women or those with thyroid problems and is not effective in killing cryptosporidium. You also won’t get any kid to down water treated with iodine, which is why I don’t recommend it for a family survival kit. A more palatable alternative to iodine is Potable Aqua’s Chlorine Dioxide tablets. This will give the water a taste similar to bleach (or a swimming pool; and who doesn’t like the taste of a swimming pool?). The treatment time is longer with these tablets but the taste is better than iodine.


Try out a few different brands at home to sample the taste and to make sure there are no side effects before you and your family rely on them in a crisis. Out of these four methods, I would recommend purchasing a water filter like the MSR which will handle chemical contaminants and then getting a couple bottles of bleach for handling bacteria and viruses. Along with boiling water on your stove (assuming there’s access to utilities), you will have three means of purifying water and staying hydrated. As we’ve found on our desert survival courses, if you don’t stay hydrated you’ll become like beef jerky.



  1. A 210-gallon water tank that collects rainwater off the roof
  2. Two 55-gallon poly-barrels with accompanying hand-siphons
  3. Six 7-gallon cubes behind a shed (north-facing). At the bare minimum, get two of these blue cubes, and you will have 14 gallons of water which will last one person seven days or a family of four for three days.
  4. A number of 1-gallon containers in the form of iced tea bottles. We have a few of these on hand around the property and one in each vehicle.



Editor’s note: A version of this article first appeared in the 2013 print issue of American Survival Guide.

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