Emergency Water Filtration

Emergency water filtration is a skill everyone should learn how to do. Whether you’re planning a camping trip, traveling, or just want to be prepared in case of an emergency, being able to filter water can be a lifesaver. There are a variety of methods you can use to filter water.  Portable purifiers are easy to use and can provide clean and safe drinking water in any environment.  Read on to learn the various ways to filter water and how it can help you stay safe in times of need.

Last month I wrote about the importance of having some water stored up for emergencies, but what if you don’t have any? Read on to see what you can do if you don’t have a supply of emergency drinking water.

What is Emergency Water Filtration

Emergency water filtration is a process of purifying water for drinking or other purposes.

Why is it Important?

It is an important part of emergency preparedness and can be used in the event of natural disasters, civil unrest, or other emergencies.

Filtering can remove contaminants from the water such as bacteria, viruses, parasites, and chemicals. This filtration process helps to ensure that the water is safe for drinking and other uses. Emergency water filtration systems are also used in developing countries where access to clean drinking water may be limited. By using these systems, people can have access to clean and safe drinking water even in times of crisis.

Types of Emergency Water Filtration Systems

Having an emergency water filtration system is essential in any survival situation. There are several ways to filter water, ranging from simple portable water filters to more complex water purifiers.  In this article we are going to cover:

  • Filtering
  • Boiling
  • Purification Tablets
  • UV Sanitizers
  • Bleach

Knowing the different ways of filtering water in an emergency and how to use them is important for anyone who wants to be prepared in a survival situation.

How to Filter Water in an Emergency

We all know water is essential for life, but sometimes we may find ourselves in a situation where clean water is not readily available. This could be due to a natural disaster, a power outage, a camping trip, or any other scenario where the water supply is compromised or inaccessible. In such cases, it is important to know how to filter water in an emergency situation, so that we can avoid dehydration and waterborne diseases.


Filtering is a common way to treat water to make it safe to drink, cook or clean with.  There are 3 common ways to filter water:

Filter straws

Water filter straws are portable devices that can purify water from natural sources, such as rivers, lakes, and streams. They use activated carbon or hollow fiber membranes to remove bacteria, protozoa, and other contaminants that can cause diseases. Water filter straws are useful for outdoor activities, such as hiking, camping, and traveling, as well as for emergency preparedness and survival situations. Some water filter straws can filter up to 100,000 gallons of water before needing replacement, while others have a lower capacity. Water filter straws are easy to use: you just insert one end into the water source and suck from the other end like a regular straw.

emergency water filtration

Bottle filters

Like the filter straws, there are bottles that have a built-in filter that removes pathogens and other contaminants as you drink from them. Some examples are Brita, Epic Nalgene OG and Lifestraw Go bottles, which can filter up to 100 gallons of water per filter. Bottle filters are portable and convenient, but they may not have a high flow rate or capacity.  The filters can be replaced as needed after their limit is reached.

emergency water filtration

Gravity filters

These are devices that use gravity to pull water through a filter cartridge that removes pathogens and other contaminants. Some examples are PortaWell and Big Berkey filters, which can filter up to 3,000 gallons of water per cartridge. Gravity filters are easy to use and do not require electricity or chemicals, but they may be bulky and expensive.

emergency water filtration

Building a homemade water filter

You can make your own gravity filter if you have the right materials.

Basic (Cloth)

One of the easiest ways to filter water is to use a cloth and a container. You can use any clean cloth, such as a bandana, a shirt, or a towel. You can also use any container that can hold water, such as a bottle, a cup, or a bowl. Here are the steps to follow:

  1. Cut or tear the cloth into a square that is large enough to cover the opening of the container.
  2. Place the cloth over the opening of the container and secure it with a rubber band or a string.
  3. Pour the water slowly over the cloth and let it drip into the container.
  4. Repeat this process until you have enough filtered water.

This method will remove some of the dirt and debris from the water, but it will not remove bacteria, viruses, or chemicals. To make the water safer to drink, you should also boil it for at least 10 minutes or add some disinfectants, such as chlorine tablets or iodine drops.

Better (Charcoal, Sand, Gravel & Cheesecloth)

Another way to filter water is to use sand, gravel, charcoal and cheesecloth. You will also need two containers, one with a hole at the bottom (an inverted 2 liter bottle with the bottom cut off works great) and one without. Here are the steps to follow:

  1. Fill the container with a hole at the bottom with layers of sand, gravel, and charcoal. The charcoal should be on top, followed by the sand, and then the gravel. The layers should be about 2 inches thick each.
  2. Place the container with the hole over the other container without a hole.
  3. Pour the water slowly over the upper container and let it drip into the lower container.
  4. Repeat this process until you have enough filtered water.
emergency water filtration

This method will remove more dirt and debris from the water than the cloth method. It will also remove some of the bacteria, viruses, and chemicals from the water. However, it will not remove all of them. To make the water safer to drink, you should also boil it or add disinfectants.


This is one of the simplest and most effective ways of killing pathogens (bacteria, viruses, and protozoa) in water. According to the US EPA, water should be brought to a rolling boil for at least one minute, or three minutes at altitudes above 5,000 feet (1,000 meters). Boiling does not remove other contaminants, such as heavy metals, salts, and chemicals, so it may not improve the taste or smell of the water. To improve the taste of boiled water, you can add a pinch of salt, or pour it from one container to another several times. Prior to boiling you may want to filter the water as well.

Purification Tablets

Water purification tablets are small tablets that contain chemicals that can kill harmful microorganisms in water. They are used to make water safe for drinking, especially in emergency situations, outdoor activities, or travel. Water purification tablets are easy to use and can treat water from various sources, such as lakes, rivers, rainwater, or taps. However, water purification tablets may not be effective against some types of parasites, such as cryptosporidium, and they may leave an unpleasant taste or odor in the water. Therefore, it is important to follow the instructions on the package carefully and use other methods of water treatment if possible.

emergency water filtration

UV sanitizers

These are devices that use ultraviolet light to kill pathogens in water. Some examples are Steripen and Purewell sanitizers, which can treat up to 50 liters of water per charge. UV sanitizers are fast and effective, but they do not remove other contaminants or improve the taste or smell of the water. They also require batteries or solar power to operate.

emergency water filtration


Bleach is one of the original methods for purifying water but is not as common these days due to both the risk of serious injury or death if not properly done and the ease of access to and use of other methods described above. You should only use bleach to purify water in an emergency situation, when you have no other safe sources of water available.

Caution: Using bleach to purify water can be dangerous (even deadly) if not done correctly. Bleach contains chlorine, which can kill harmful bacteria and viruses in water, but it can also harm your health if you ingest too much of it.  Here are some steps to follow if you need to use bleach to purify water:

  1. ONLY use regular, unscented bleach that contains 5% to 6% sodium hypochlorite.
    • DO NOT USE scented, color-safe, pens, or bleach with added cleaners.
  1. Filter the water through a clean cloth or coffee filter to remove any dirt or debris.
  2. Add 1/8 teaspoon (or 8 drops) of bleach per gallon of water (double the amount if the water is cloudy, colored, or very cold).
  3. Stir well and let it stand for 30 minutes before drinking.
  4. If the water does not smell slightly of chlorine after 30 minutes, repeat the process and wait another 15 minutes.
  5. If the chlorine taste is too strong, you can reduce it by pouring the water from one container to another and letting it stand for a few hours.
  6. Store the purified water in clean, covered containers and use it within 24 hours.

Remember, using bleach to purify water is only a temporary solution. You should always try to find a more reliable and safe source of water as soon as possible.

Tips on Storing Filtered Water

Once you have gone through the trouble of filtering water, make sure you store it properly, so it stays safe to drink and cook with. Here are some tips for storing purified water:

  • Use clean and sanitized containers. Avoid using plastic bottles that have been exposed to heat or sunlight, as they can leach chemicals into the water. Glass or stainless steel containers are better options.
  • Store the containers in a cool and dark place. Avoid direct sunlight, heat sources, or freezing temperatures, as they can affect the taste and quality of the water. A basement, closet, or pantry are good places to store purified water.
  • Seal the containers tightly. Prevent air, dust, or insects from entering the containers, as they can contaminate the water. Use screw caps or lids that fit snugly on the containers.
  • Label the containers with the date of filling. Purified water can last for up to six months if stored properly, but it is still a good idea to keep track of when you filled the containers. This way, you can use the oldest water first and avoid wasting any water.
  • Replace the water every six months. Even if stored properly, purified water can lose its freshness and quality over time. It is recommended to replace the water every six months or sooner if you notice any changes in taste, odor, or appearance.


There you have it.  We covered why you need it and some of the most common methods of filtering water in an emergency situation, but there may be other options depending on your situation and preferences. Whatever method you choose, make sure you follow the instructions carefully and test the quality of the water before drinking it. Remember that filtered water may not be safe for long-term storage or consumption, so always use fresh sources whenever possible. 

Additional Reading

Last Updated on August 5, 2022