How to Filter and Purify Water for Survival

Note: This post is part of the Prepared Blogger‘s 30 Days of Preparedness series to celebrate National Preparedness Month.

Day 26: How to Filter and Purify Water for Survival

Water is essential to survival. If there is one survival skill you should learn, I would recommend how to filter and purify water so it’s safe enough to drink. You just never know when you might end up in the woods by yourself with dirty water, hopefully never, but it can happen 😉

There are so many different definitions and ways on how to filter and purify water, but I’ll try and keep it simple. The main thing you need to do is filter out the big stuff, and then purify the water from any lurking bacteria, germs, or other harmful things that could make you sick and do more damage than good.

Filter + Purify = Drinking Water

Ways to FILTER Water:

Filtering is the removal of all “visual” particles and matter from the water such as dirt, leaves, insects, etc so it can be properly purified and then safely consumed.

Basic Filtering Options

The simplest levels of filtration can be achieved by running water through coffee filters, layers of paper towels, a tightly woven cloth, a bandana, or anything that will remove the big stuff you can see. You can also help filter the water by allowing it to settle for awhile to allow the heavy particles settle to the bottom, then pouring the water into another container.

DIY Water Filters

There are plenty of DIY water filters you can find by just searching the internet. The best part is most of them only need a few materials you can find laying around.

  • DIY Gravel & Sand Filter – This video demonstrates how to make a water filter using – a bottle, activated carbon, a cotton ball, sand, & gravel.

Ways to PURIFY Water

Purifying is the removal of all “invisible” bacteria, germs and other harmful elements from the water so it can be safely consumed.


One of the most common methods for purifying water is to boil it. Everyone varies on how long to boil from 1 to 10 minutes. When water boils, any bacteria that may have been living in it will be killed, thus reducing your chance of getting sick when you drink the water. When done boiling, remove from the heat source, cool and drink. Remember, boiling will not remove contaminants such as heavy metals, salts, and chemicals.


To pasteurize water it needs to be heated to 149 degrees Fahrenheit for several minutes. A way to check that pasteurization took place is to use a WAPI (Water Pasteurization Indicator). WAPIs are small plastic tubes with industrial grade wax inside of them that melts when water is heated to 150 F for more than fifteen seconds. This method will also not remove contaminants such as heavy metals, salts, and chemicals.


Most people don’t like the thought of using chemicals to purify their water, but in worst case scenarios you may have no other option. When using chemicals you need to make sure you’re using them correctly, and not for long periods of time (usually no more than 3 months).

Bleach – Be sure to use bleach that has no additives, such as scents, soap, or phosphates. Bleach has a very short shelf-life (about 6 months), it loses potency and becomes less effective. Add 1/8 tsp per gallon if the water is clear. Shake it up thoroughly, and let sit for at least one hour before consuming. The water should still smell slightly of chlorine. If you cannot smell chlorine after 30 minutes, repeat the process. 

Calcium Hypochlorite – This chemical can purify water in the event of an emergency and can last for 10 years if kept in a cool, dark place. It’s more commonly known as pool shock and a single pound of it will disinfect about 10,000 gallons of water. Be sure to purchase shock that has at least 68% calcium hypochlorite in it.

This is a 2 part process:

  1. Add one heaping teaspoon of the powdered chemical to two gallons of water and allow to dissolve to make a chlorine solution (this makes Homemade Liquid Bleach).
  2. Now, add this solution to your drinking water at a ratio of one part solution to 100 parts water (approximately one pint to each 12.5 gallons of water to be disinfected).

To help remove any objectionable chlorine odor, aerate the disinfected water by pouring it back and forth from once clean container to another. It’s also a good idea to have a pool test kit to ensure any water purified with this method doesn’t obtain too much chlorine.

Iodine –  This is available in tablet, liquid and crystalline forms. Pregnant women and those with thyroid problems should not use iodine! Also, long-term use is not recommended. Use five drops of 2 percent iodine for each quart of water, or 10 drops if the water is particularly cloudy. Let stand for one hour before drinking.

Chlorine Dioxide Water Purification Tablets – These tablets requires about four hours to react. They have a shelf life of four years when properly stored and can improve the taste of water.  One tablet will purify one quart of water, but follow the directions on the package to ensure that you’re using the tablets correctly.

Solar Water Disinfection (SODIS)

The SODIS method uses ultraviolet rays over time to kill bacteria. Use clear plastic bottles and fill them with filtered water. Place the bottles on a dark surface in the sun to increase temperature. Leave in the sunlight for about six hours, or for 2 days if it’s cloudy. You can visit for more information about this method.


Again, there are numerous was you can distill water and a lot of them you can do yourself. The great thing about distilling water is you can use almost any liquid – including urine and even salt water from the ocean.

DIY Water Still

DIY Water Stove Still

Portable Water Filters & Purifiers for Survival:

If you don’t want to be stuck trying to make your own water filter or purifier, here are some of the most popular options below. Each of these are small enough to add to your survival kit or bug out bag so you’ll never have to worry about going thirsty.

lifestraw-personal-water-filterLifeStraw Personal Water Filter

Filters up to 1000 liters of contaminated water WITHOUT iodine, chlorine, or other chemicals. It features a high flow rate and weighs only 2oz. Shelf life has been extended to 5 years. Please NOTE: It takes roughly 3-5 seconds of sucking to start the flow of water through the filter.

potable-aqua-water-treatment-tabletsPotable Aqua Water Purification Iodine Tablets

Iodine tablets designed to make contaminated water suitable for drinking. Intended for short-term or limited emergency use only. Water is ready within 30 minutes; neutralizes iodine aftertaste and color.

uv-water-purifierSteriPEN UV Water Filter

Compact handheld UV water purifier designed specifically for outdoor/expedition use; up to 8,000 16-ounce treatments. Safe and effective without altering taste, pH, or other properties of water; chemical-free. UV lamp can be used as an LED flashlight.

purificup-portable-water-filterPurifiCup Portable Water Filter

PurifiCup eliminates more than 600 kinds of bacteria, providing you safe and clean water. The silver membrane utilizes silver’s natural anti-bacterial and anti-fungal properties to filter the water, so there is no need for boiling after it is filtered and each filter provides 100-150 cups of pure drinking water. Both a water filter and storage bottle, and requires no hoses or attachments.

katadyn-water-filterKatadyn Water Filtration System 

Combines the two best technologies – ceramic and pleated microfiltration Ultra fast flow (2 liters/minute). Replaceable carbon so water always tastes fresh. Replaceable carbon core reduces chemicals, pesticides and bad taste in water. Output: Up to 2 quart (2 liter)/minute. Cartridge Capacity: Up to 500 gallons (1875 liters), depending on water quality.

Berkey-filterGo Berkey Filtration Kit

This powerful system purifies both treated water and untreated raw water from such sources as remote lakes, streams, stagnant ponds and water supplies in foreign countries, where regulations may be substandard at best. Perfect for outdoor activities and a must in hostile environments where electricity, water pressure or treated water may not be available.


Here’s a handy guide on the Berkey Water Filter that can help explain more!

How Do You Plan to Filter and Purify Water?

Be aware that with most of these methods the water is not always 100% free of chemicals, heavy metals, salt, etc. Even some of the big expensive purifiers can’t remove all the different chemicals. Make sure to do your research on the method you choose to use and pay attention to what may be lurking in the water you plan on purifying.

P.S. Be sure to check out the rest of the 30 Days of Preparedness series:


Thanks for joining the Prepared Bloggers as we work our way through 30 Days of Preparedness. September is National Preparedness Month so you will find everything you need to get your preparedness knowledge and skills into shape.

Take one post each day, learn as much as you can about the topic and make it a part of your preparedness plan.

Day 1Ready, Set, Get Prepared! Welcome to 30 Days of Preparedness from PreparednessMama

Day 2The Family Meeting Place and Escape from Laughingbear Adventures

Day 3I’m Safe! How to Communicate with Family in an Emergency from PreparednessMama

Day 4Does Your Family Have a Fire Escape Plan? from Home Ready Home

Day 5Preparedness For Pets from The Busy B Homemaker

Day 6The Escape Exercise from Laughingbear Adventures

Day 7It all Falls Apart Without Mental Preparedness from PreparednessMama

Day 8It’s a Matter of Emergency Kits from A Matter of Preparedness

Day 9Nine Great Emergency Light Sources Other Than Flashlights from Food Storage & Survival

Day 10 Cooking Without Power from Mama Kautz

Day 11The Importance of a Shelter & Staying Warm and Dry from Trayer Wilderness

Day 12The Importance of Having The Right Tools In Your Pack from Trayer Wilderness

Day 13Practice Living Without Electricity from Food Storage Made Easy

Day 14How We Choose The Right Gear – (including the MultiFlame Tool) from Trayer Wilderness

Day 15Water Storage & Purification from The Busy B Homemaker

Day 16Food and Water for a 72 Hour “Go Bag” from Homestead Dreamer

Day 178 Foods You Should Be Storing and How from Melissa K Norris

Day 18 – Planning Your Pantry from The Organic Prepper

Day 19Stocking Up on Non-Food Items from Living in Rural Iowa

Day 20Dutch Oven Cooking: Off-Grid Before Off-Grid Was Cool from The Backyard Pioneer

Day 21Preserving and Canning the Harvest from Timber Creek Farm

Day 22Personal Protection & Awareness from Living in Rural Iowa

Day 23KISS First Aid from Herbal Prepper

Day 24Mommy, I have to go Potty! from Mom With a Prep

Day 25Fire Starting 101: The Why and How of Lighting a Fire for Survival from Food Storage & Survival

Day 26How to Filter and Purify Water from Prepared Housewives

Day 27How To Make A Shelter from Trayer Wilderness

Day 28Put Your Preps to the Test with 24 Hours Unplugged from The Organic Prepper

Day 29What Is Char and Why You Should Have It To Start A Fire from Trayer Wilderness

Day 30How To Utilize Bushcraft Skills and Forage From The Wild from Trayer Wilderness

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