All About Water Purification: A Complete Tutorial

Having water on hand is just one part of being prepared. Knowing how to safely store, treat, filter and purify water can keep you alive. To know how much water to have on hand and how to store it, read Water Storage 101. This article reviews how to make sure water is safe to drink. You can get very, very sick from drinking contaminated water, and in a survival situation, sickness can quickly become a life or death scenario. You need water, but more importantly, you need safe drinking water.

If you have water stored, you may be certain it is safe to drink, but if you’re using other supplies of water from inside or outside of your home, for instance, from a pond or a natural spring (or you want to make extra sure your water storage is safe), you’ll need to filter and purify it. Should you drink the water? It’s important to know for sure.

Treating stored water

Water bottles and water stored from a safe drinking supply (tap water from a municipal plant) should be fine to drink. Other stored water, such as from a well, needs to have bleach added to it to treat it. The Survival Mom recommends using 1/8 teaspoon of bleach with no additives per gallon if the water is clear.

You should keep some unscented bleach on hand for emergencies, but be aware that bleach does have a fairly short shelf life. It starts to break down after six months and needs to be replaced every 12-16 months. Rotate your bleach bottles frequently to ensure you have effective bleach on hand.[aweber-form]

Making water potable requires two steps, filtering and purifying. Filtering removes bits of things, like sand and bugs. It removes big particles, not microscopic ones like bacteria. Purifying removes or kills germs and bacteria, although some methods are more effective than others.

Filtering first and then purifying is the best practice for drinking water, in part because it extends the life of your purifier and in part because some purification methods (such as boiling) do absolutely nothing to filter out debris.

Filtering water

Tap water can become contaminated even in non-emergency situations but more commonly in an emergency. In a non-emergency, you will almost certainly find out either from news stories or when you receive a phone call notifying you to boil your water to make it potable. (Potable water can be safely consumed.) In a true emergency, it is safest to treat your water source as likely contaminated until proven otherwise.

You may have to seek water sources inside your home, like the water heater, or outside the home, like a pond or stream. Water from sources that aren’t guaranteed to be safe should be filtered first and then purified. Filtering removes big impurities like leaves, dirt, insects, and sticks. Towels, screens and coffee filters can be used to filter water. Another way to do it if you don’t have those items on hand is to improvise a water filter that lets the water flow through layers of rocks, sand, and charcoal to filter out debris.

Sometimes commercial “filters” are actually purifiers. It is important to do both steps, so make sure you look closely at what the product actually does because you need both. If it is a purifier, then you need to add a filter – unless you enjoy spider legs and leaves in your drinks.

Purifying water

Once water is filtered, there are several ways to purify it. You can boil it, add bleach, use calcium hypochlorite, use UV light, add water purification tablets, or use a commercial device.

Boiling water can be a great way to purify water, but it does have a couple of downsides. First, it can concentrate any chemical contaminants in the water. As water evaporates as steam, it will leave behind liquid water that may contain a more concentrated level of certain contaminants.

Another downside is that it requires fuel and time for the water to come to a full boil. If either is in short supply, boiling won’t be your best bet.

Otherwise, you want to heat the water to 149 degrees for 1 minute to pasteurize it. Pasteurization actually occurs at a lower temperature than boiling, but you’ll need either a thermometer to verify the water temperature or a WAPI, Water Pasteurization Indicator. This inexpensive device is a handy addition to any emergency kit.

Adding bleach to water can also treat it for some pathogens. The American Red Cross actually recommends boiling and using bleach. If you want to add bleach to water that has been boiled, make sure it has been cooled down first. The water should have a slight chlorine smell once bleach has been added and allowed to sit for at least 30 minutes or so. If you do not smell a bit of chlorine, add another drop or two.

Use this chart for reference when using bleach:

Water amount                      Cloudy Water                         Clear Water

1 quart                                    4 drops bleach                        2 drops bleach

1 gallon                                   16 drops                                   8 drops

5 gallons                                 1 teaspoon                               ½ teaspoon

55 gallons                               4 tablespoons                         2 tablespoons

Since bleach has a shelf life and begins to lose its effectiveness after just a few months, write the purchase date on the bleach bottle using a black Sharpie. This will be a reminder each time you see that bottle that you need to start using it and replace it with a new bottle about 6 or 7 months following the purchase date.

Next, with that same Sharpie, write, “8 drops per gallon water, 16 drops cloudy water,” on the bottle. With this information right in front of you, you won’t be rummaging around looking for these amounts in an emergency.

Finally, duct tape an eyedropper to the side of the bleach bottle. These are very inexpensive online and are found in drug stores and usually in the over-the-counter medicine aisle in the grocery store.

A handy eyedropper will make sure that you’re using the correct amount of bleach, and you won’t have to resort to using an eyedropper from another medication.

Calcium hypochlorite has a longer shelf life than bleach but is also trickier to use for purifying water. You can often find it labeled as pool shock, but make certain it doesn’t have any extra additives. (It needs to be safe to purify water for drinking, not just for swimming in.) The Survival Mom recommends Cal-Shock 65. You can read in-depth about pool shock here. When using pool shock, you make a solution of homemade bleach with a teaspoon of pool shock and 2 gallons of water. (A pool test kit comes in handy to make sure the right amount is added.) To purify water with the homemade bleach solution, add 1 ¼ teaspoon to 1 gallon of water.

UV light can purify water. The battery-powered SteriPen uses UV light to purify small amounts of water. There is also a hand-crank version of the Steripen.

Another option for purifying water is the use of water purification tablets. These are good short-term methods since they contain iodine. They are a good addition to a vehicle or bug-out bag since they are small and lightweight. However, iodine should not be used for more than six weeks and not by pregnant women. As with boiling, it is effective against many pathogens, but not with chemical pollutants.

There are also many commercial water purification devices that you can have on hand. There is the LifeStraw, Katadyn, Berkey, Survival Still, and many others. They can easily be added to any bug-out bag or vehicle as well. Some can be used for large quantities of water, while others are designed to be used by one person.

Well considerations

If you have a well for water, you should test it regularly, especially if you haven’t used it for several weeks, if new equipment has been installed, there has been flooding or an earthquake, or it smells, looks or tastes funny. If you have a new well pump installed, the hoses that actually go into the well – in your water – will be laying on the ground before being put down into the well. This means they will potentially be covered in who knows what from the ground. It is extremely important to have a professional (the ones installing your well) treat the water with high doses of chlorine to kill any germs and bacteria.

Your water will not be potable until the chlorine level goes down, so be prepared to use bottled water for drinking. Keep enough bottled water on hand, both in small and large containers, for any time that your well water might become contaminated or your well pump stops functioning.

When you have a new pump installed, well water should be tested again after two weeks to ensure it is bacteria-free and safe to drink. Depending on the filters in your home, you may be able to drink it sooner. In our home, we have a sediment filter, a whole-house UV filter, and a reverse osmosis filter for our primary drinking water. We were able to drink the water after the chlorine smell went down (two or three days) but still needed to be certain the water was safe just in case our UV filter failed.

Very few people have whole-house UV filters, but they do add peace of mind for a few hundred dollars. There is no denying it’s an expense, but it kills micro-organisms that filters don’t affect. Three filters may sound like overkill, but once when an earthquake caused our neighbors’ well water to become brown and undrinkable, our multiple filters left us unaware of the problem until we heard them talking about it. It is worth being certain.

Wells can be a great source of water in an emergency, but you need to have a way to get the water up when the power is out. Consider getting a backup system that uses a generator, solar power, or a hand pump. Well pumps actually use quite a bit of power, so check your requirements and the generator capacity carefully.

Swimming pool water

If you have a swimming pool, you may think you have a great source of emergency water, and you do – for anything other than drinking or cooking. Pool water may contain chemicals that act as a laxative and can be toxic over a long period of time. Chlorine-resistant bacteria can be in the water from the bodies of people who have swum in the pool.

Believe it or not, I had a tough time finding experts who could answer my questions about safety issues and drinking pool water. Even National Terror Alert.com gave a confusing answer:

You should always view your pool as “backup” water; keep it treated; you never know when it will be needed! The maintenance of the free chlorine residual will prevent the establishment of any microorganisms. The maintenance level should be kept about 3-5ppm free chlorine.  If other stored water stocks are not available, remove the necessary pool water and boil it or just treat with chlorine to the normal 5ppm. It is best to err on the side of caution.

Robin Bain from the City of Peoria (Arizona) water department provided some good insight into the safety of pool water for drinking. She informed me that when water leaves the treatment plant, it contains between 1 and 1.5 mg chlorine residual per liter.  The chlorine residual is in a form that can continue disinfecting the water as it passes through the pipes on its journey to your home.  Chlorine is necessary to kill any type of pathogens that may exist in the pipes.

She went on with her explanation, stating that chlorine dissipates very quickly in the sunlight and is consumed by its’ reaction with the air and sunlight. Additional chlorine is added to pool water to keep algae away and sanitize the water from any germs or other yucky things tracked in by people. She informed me that the chlorine isn’t the problem.  The problem is the stabilizer added to pool chlorine. This stabilizer keeps the chlorine from evaporating as quickly, but the stabilizer never evaporates. The only way to reduce the amount of stabilizer in your pool water is to drain the pool, partially or completely, and refill it with fresh water.

Alan Martindale, Water Quality Supervisor for the City of Mesa (Arizona), says there are four very important reasons to not consume swimming pool water, other than a gulp or two by accident when splashed in the face by your toddler.

1. High total dissolved solids (mineral content such as chlorides, sulfates, calcium, and magnesium) can cause a laxative effect, not a good problem to have in an emergency!
2. Treatment chemicals are not safe for long term ingestion.  Pool chlorine is often stabilized with cyanuric acid, a derivative of cyanide.
3. Chlorine resistant critters such as Giardia and Crypto (typically from pets)
4. Portability,  many emergencies could require mobility,  can’t move pool water very easily

Additionally, a power outage will shut down your pool’s pump and filtration system, leading to the growth of algae and other microbes within a few short days.

So what is pool water good for, besides swimming?  It’s useful for bathing, flushing toilets, and perhaps, doing laundry.  Actually, this is very good news for pool owners, since it means you only need to worry about storing water for drinking and cooking purposes.  In an emergency, all that pool water will definitely not go to waste!

Pool water is also a type of water that shouldn’t be purified by boiling, as it will increase the concentration of the chemicals and minerals it contains. If there is no power for the pool’s pump and filter system, it could start to become a breeding ground for insects and algae. Having pool test kits on hand can help you know if the chlorine levels are set right to prevent mosquitoes. The water can be used for laundry, flushing toilets, and washing animals.

Be safe when drinking water in emergencies. You need water – clean water – to survive any emergency situation!

More resources for water purification

• Big Berkey Water Filtration System — dependable brand, recommended
• Katadyn Gravity Water Filter — 1 to 6 persons
• Lifestraw Personal Water Filter — inexpensive and lightweight
• The Prepper’s Water Survival Guide by Daisy Luther
• Sawyer Mini Water Filter — a good size for emergency kits. I keep one in my suitcase for family travel.
• Survival Mom: How to Prepare Your Family for Everyday Disasters and Worst Case Scenarios by Lisa Bedford