How to Maintain a Safe Water Supply

essential skills water supply Nov 10, 2020
safe water supply

Because water is a basic need you simply cannot live without, maintaining a safe water supply is essential. It is one of the most important elements for being self sufficient. Most healthy adults can survive about three to four weeks without food. However, you can only last 3 to 4 days without water.

Besides, in order to be properly prepared for an emergency situation, you must always have access to a safe water supply.  For example,  during a major flood event, well water, rivers, streams, lakes and ponds can become contaminated. That contamination can be in the form of chemicals, human sewage, livestock waste, as well as many other potential toxins. Consequently, best practice dictates being completely independent of any sort of infrastructure.

Furthermore, even if you are connected to the public infrastructure, this is no guarantee of a safe water supply.  The reason is that during a natural disaster it is common for the public infrastructure to be disrupted. Consequently, the ideal situation is to take matters into your own hands. This is the only way to ensure you always have access to a safe water supply.  Therefore, it is imperative that you have the ability to disinfect and purify water completely on your own.

There are a few simple but important principles to understand in order to safe guard your water. Follow these principles and you will always have fresh water in an emergency or survival situation.

Table of Contents

1) Three Steps to Maintaining A Safe Water Supply

2) Water Filtration

3) Best Practices for Using Water Filters

4) Most Common Types of Water Filters

5) Water Purification

6) Non-Chemical Water Purification Methods

7) Chemical Water Purification Methods

8) Chemical Water Purification

9) Drinking Raw Water

10) Take Home Message


Three steps to maintaining a safe water supply

There are three basic principles to follow to ensure constant access to a safe water supply. It only requires a little forethought and planning and a little financial investment. Then you will be confident and secure with safe water to drink. Be prepared to do the following three things: 

  • Water storage
  • Filtration
  • Purification and disinfection 

Water Storage

The first concern that most people have is how much water to store.  However, this varies depending on several different factors as each individual situation is unique. 

The following factors will dictate the size of your safe water supply :

  • The size of your family
  • The presence of younger family members.  Children have greater daily water requirements than adults
  • Family members with specific medical conditions
  • Environmental temperature
  • Your daily activity level
  • Pets that require daily water intake
  • Personal hygiene needs
  • Cleaning, such as washing dishes  

To be very specific, the basic daily water requirements for adults is about 1/2 oz per pound of body weight.  Children are about twice that amount.  However, as a general guideline, allow one gallon/day/person for basic needs. Allow 2-3 gallons/day/person for personal hygiene, washing dishes, etc. Keep sufficient water to last each person two weeks. Store the water properly and rotate it regularly. 

At the low end, for two people this equals 28 gallons of water to last two weeks.  At the high end, it equals 84 gallons. 

Proper storage

Proper storage to ensure a safe water supply is actually very simple. Again there are just a few basic principles to follow and you will be well on your way to always having safe water supply.  Keep the following points in mind: 

  • Store water in a clean, dark, cool place that is free of possible contamination. Otherwise it is possible for harsh chemicals, odors, fumes, and smoke to leach into the water.
  • Always start with clean, uncontaminated water.  If stored properly, it will keep for years. Although water does not really “go bad”, it can take on a stale taste after years of storage. Regular rotation will prevent this from happening. 
  • If storing water in plastic containers, place those containers on a clean, dry, uncontaminated surface. Plastics can leach odors and chemicals from the surface they are sitting on. For this reason, it is not recommended to place containers directly on concrete. Place them on top of untreated wood as an alternative. 
  • Always store water in clean food grade containers. Containers specifically made for water storage is best. Plastic is the most common type of container used because it is inexpensive and easy to obtain.

Additionally, try not to use plastic containers that have been used for another food product.  Flavors and odors from those products will leach from the plastic. This will result in a bad taste.  Plastic power aide, gatorade, and cola bottles are safe to use if you do not mind the flavor leaching into your drinking water. 

CAUTION: Do not re-use plastic milk containers. No matter how much you clean these containers they can still contain left over milk cultures and proteins that have leached into the plastic. These cultures and proteins will promote the growth of bacteria. 

Safe Water Storage Tips

  • BPA free containers are not necessarily better.  The alternatives to BPA that are being used in plastics are not any better or worse for you. Do your homework and decide for yourself.  
  • Use containers of several different sizes. Of course the best way to store a larger safe water supply is by using 55 gallon drums.  However, water weighs 8.36 lbs/gallon, or 1 kg/liter. A 55 gallon drum of water = 459.8 lbs = you’re not moving it. If you decide to use 55 gallon drums, it is important to be able to siphon water into smaller containers that are easily portable. Make sure to have several drums in the event that one is damaged. Otherwise if one drum leaks you risk loosing your entire safe water supply. 
  • Not all water storage containers are stackable. This includes the plastic 55 gallon drums.  Check the product description. There are products on the market that are specifically made for stacking.  But, they also have limitations on height and weight. They are also a lot more expensive. 
  • Divide your water storage between several different places in the event one storage area is destroyed.  

Water filtration versus purification

Storing a certain amount of water is an important first step to always having a safe water supply.  However, it is just as important to have backup methods to maintain that supply.  This is especially true if you are forced to live without access to a public infrastructure for an extended period of time. Consequently, being able to filter and purify water is extremely important.  

Water filtration and purification are technically different. Knowing the difference will help guide you to purchasing the proper equipment.  There are products on the market that combine both of these processes. However, those products are more expensive.  In most cases, filtration and purification is a two step process. Therefore, it is of value to discuss each process separately.  

Water Filtration 

At the most basic level, water filtration is simply removing impurities through the use of a physical barrier. Filtration systems remove sediment and even tiny particles such as bacteria, viruses, and microbial cysts.  Filtration generally precedes purification. This is because excess sediment or microbial content influences the purification process. Additionally, starting with relatively clean water aids significantly in the purification process.  Besides, cloudy, turbid water that contains a large amount of debris and sediment will quickly clog any filter.  

There are literally hundreds of different brand names and sizes of filters to choose from. Portable models are generally hand operated or gravity fed.  Larger ones designed only for home use often require electricity or water pressure. Do your homework and make certain the model you choose actually suits your needs. Personally I would always opt for something that operates as a stand-alone unit. This means you are not dependent on water pressure or electricity to provide you with a safe water supply. 

Water filters do require periodic maintenance and even replacement.  Know the requirements and limitations of the filter you are using.  Improper maintenance can result in bacteria build up and growth within the filter element.  Charcoal filters are especially prone to this.

Filtration systems are capable of removing protozoa, bacteria and viruses. However,  filtered water is susceptible to recontamination. Therefore, if it is going to be stored for any length of time, filtered water needs an additive to provide ongoing protection.  That is the rationale to adding chlorine to municipal drinking water systems. Viruses and bacteria that come in contact with chlorine are inactivated. Consequently, the water remains safe to drink and can be stored for a long period of time.  

Filtered water that is consumed in a reasonable amount of time generally needs no further processing.  However, to be completely safe, I would strongly recommend that filtration be followed  with purification/disinfection. This additional step will help ensure the complete removal of biological contaminants. Although there is no guarantee, this two step process is the best way to ensure a safe water supply. 

Best Practice for Using Water filters 

  • Start with the cleanest water you can find. Cloudy, turbid water with a lot of suspended particles will quickly clog any filter. 
  • If filtering dirty water is your only option, place the water in a 5 gallon bucket or other large container and allow it to stand undisturbed overnight.  
  • Pre filter water.  Some filtrations systems have a built in pre filter. If not, filter the water through cheese cloth, a coffee filter, cotton ball at the bottom of a funnel, a bandana, cloth towel, etc. Whatever material you use, make sure it can be washed, flushed and re-used. 

Most common types of water filters  

  • Ceramic filters
  • Active carbon or charcoal filters
  • Ion exchange resins
  • Reverse osmosis
  • Cartridge filtration
  • Ultraviolet sterilization
  • Combination units using one or more filtration methods.

Common organisms and the filter size needed:


  • Types: Giardia, Cryptosporidium, Entamoeba histolytica 
  • Size range: 1.0 to 300 microns
  • Filter size needed: 1.0 to 4.0 microns



  • Types: Cholera, E. coli, Salmonella, Typhoid (Salmonelly typhii), Shigella, Campphlobacter, Leptospira
  • Size range: 0.1 to 20 microns
  • Micro filter from 0.1 to 20 microns


  • Types: Hepatitis A, rotavirus, Norwalk virus, Adenviruses, Enteroviruses, Polio, Dengue Fever
  • Size range: 0.005 to 0.1 microns
  • Use a water purifier to 0.004 microns

Water Purification

Water purification is often needed to ensure a completely safe water supply. It aids in the  complete removal of biological contamination. Some organisms, especially viruses, are extremely small. Many filters on the market these days will not remove them. Although not always true, water purification is most often a chemical process. There are non-chemical methods, which are discussed below. However, the chemical methods of purification are often much more efficient.  

Non Chemical Water Purification Methods

  • Boiling

Boiling water is a widely used, effective means of water purification. Most health departments recommend bringing the water to a rolling boil for one minute.  At elevations greater than 5280 feet (1584 meters), the recommendation is a rolling boil for three minutes. This will eliminate all bacteriological contaminants. However, boiling will not remove chemical contaminants. 

In most cases, water from lakes, ponds, natural springs, rivers, streams, as well as rain water, is safe to purify by boiling.  Cloudy water should be filtered before boiling.  In an emergency, this can be done by using coffee filters, paper towels, cheese cloth, or using a cotton plug stuffed in the bottom of a funnel. 

Although boiling is effective, using this method has it’s challenges and limitations.  You obviously need a heat source, whether that be electricity or fire.  Consequently, in an emergency situation this may not be practical.  Additionally, if you are in a survival situation with limited resources, you may not necessarily want to constantly use fire or any other source of heat solely for the purpose of water purification.

  • Solar Water Disinfection (SODIS)

SODIS was first developed in the 1980s as an inexpensive means of household water treatment. In 1991, the Swiss Institute of Environmental Science and Technology began to experiment with this is a method of household water treatment in developing countries. The information here is credited to the Swiss Federal Institute and the Center for Disease Control (CDC). 

The methods used by the Swiss involved filling 0.3 to 2.0 liter plastic soda bottles with low-turbidity water.  Once filled, the bottles were shaken to oxygenate the water and were then placed in direct sunlight.  Rooftops were commonly used.  Disinfection occurs in 6 hours in sunny conditions or 2 days in cloudy conditions.  Disinfection occurs due to the combined effects of ultra-violet (UV) induced DNA damage, thermal inactivation, and photo-oxidative destruction of disease-causing organisms.  Inactivation of viruses, bacteria, and protozoa was proven under laboratory conditions and verified under field conditions.  

The benefits of Solar Disinfection: 

  • Proven reduction of viruses, bacteria, and protozoa
  • Proven reduction of diarrheal disease incidence
  • Simplicity of use
  • No cost if using recycled bottles
  • Minimal change in the taste of the water
  • Recontamination rate is low

Drawbacks of using Solar Disinfection:

  • High turbidity water has to be pretreated or pre filtered
  • Length of time needed to treat the water
  • Limited amount of water can be treated at once
  • Large supply of clean, suitable plastic bottles is required. 

For more complete information on using SODIS, and to give appropriate credit, I have provided links to a CDC and a European website where you can download a PDF of this information.

 CDC PDF is here.

Check out this PDF as well.


  • Distillation

Distilling water is perhaps the safest way to produce a safe water supply.  In fact, the Environmental Protection Agency (EPA) describes distillation as one of the only means of “purifying” water. They regard any other method as simply being water “treatment”. Distillation with remove bacteria, viruses, protozoa, as well as salts, heavy metals and most other chemicals. 

The basic principles of distillation are simple. However, there are numerous methods for accomplishing the same thing.  Each has advantages and disadvantages. The applicability and practicality of each method depends entirely on your situation. 

Survival situation

In a survival situation where there is little if any water, setting up a basic solar distiller may be your option for water.  A survival distiller simply takes advantage of the “greenhouse” principle.  The materials needed are as follows:

  • A shovel or other device for digging a hole
  • A clean container for catching water
  • Plastic tubing long enough to be placed into the collection container and extend into the exterior. This essentially becomes a straw that allows you to retrieve water without breaking down the still.  
  • 6 x 6 foot sheet of clear plastic. 
  • A small, smooth stone

Building the still

  • Dig a square pit that measures 4 feet on each side and 3 feet deep.  This is large enough to provide a reasonable surface area for water collection. The still needs to be in an area where there is direct sun.  Also, ground water has a tendency to accumulate in small depressions due to natural run off. The still will be more productive if it is placed in a such an area. 
  • Place your collection container in the center of the hole. Dig a small hole large enough to accommodate your collection container.  This will prevent your container from tipping over once the tubing is in place. 
  • Place the tubing in your collection container and run it to the edge of your hole. It may be necessary to secure the tubing to the container.  
  • Cover the hole with the clear plastic sheet and weigh the edges down with a small amount of dirt.  
  • Place the small stone in the center of the plastic so that the plastic is weighted down toward the collection container.  It is best to have the plastic at a 45 degree angle to the surface of the ground.  But, in reality this can be estimated. 
  • Once the plastic is adjusted appropriately, weigh the edges down with more dirt to prevent it from being disturbed on windy days.  
  • Within a few hours, the air inside the still will become saturated.  The condensation will collect on the plastic and eventually drip into the collection container.  

Additional tips

Place small pieces of plant material inside the still to add moisture.  If you actually have water but it is contaminated, you can soak the ground inside the still with this water. The contaminants will not transfer to the collection container. 

The big advantage to this method is that no special equipment is required. Besides, the supplies you need are easy to transport.  The big disadvantage is that you will need several solar stills to produce a safe water supply sufficient

for a small group of people. 

Home based solar distiller

Essentially the home distiller is a closed rectangular container with a lid consisting of a glass pane at about a 45 degree angle. At the bottom of the glass pane is a collection trough.  The container is filled with water and placed on a level surface in the direct sun. 

Mother Earth News has a great article with detailed plans on how to build a solar still.

Stove top distiller

A simple stove top distiller can be made in less than 15 minutes. The Redcross and FEMA offer the following instructions: 

Fill a pot half full with water. Tie a cup to the handle of the lid so that the cup is right side up while the lid is upside down. Make sure the cup is in the center of the lid. Boil the water for 20 minutes. Water vapor will condense on the under side of the lid, run to the center and drip into the cup.




Commercial products

There are numerous home distillers on the market ranging in price from $100 to $1000. These are easy and convenient to use. The down side of course is the cost.  

The obvious disadvantage to using a stovetop distiller is that in a disaster situation you may not have electricity or the availability of dry fire wood. 

Chemical Water Purification Methods

Basic principles of chemical purification/disinfection of water:

  • The effectiveness of any chemical treatment is directly related to water clarity, pH level, and temperature. For example, colder, cloudy water will take higher concentrations of chemicals to purify than water that is warm and clear. At 50 degrees F, only 90% of Giardia cysts are inactivated after a 30 minute exposure time.  Water at 40 degrees F, treatment time should be doubled. For best practice, water should be at 60 degrees F. 
  • Water that is cloudy or contains a lot of sediment should be filtered prior to treatment.  Water can be run through a coffee filter, cheese cloth, paper towels, or even a thick cotton towel or a fine mesh T shirt if needed. This will at least remove large particle.  If straining is not an option, place the water in a 5 gallon bucket and allow it to sit undisturbed overnight. Even fine sediment will settle to the bottom with this method. It is better that nothing.   
  • Once chemicals are added to the water, stir thoroughly to make sure it is dissolved. Make sure that all surfaces of the water container are treated, including the lid and threads.
  • Purification takes about 30 minutes after the chemicals have been added. If you are using tablets, allow the water to stand for 30 minutes after the tablets have dissolved and the water has been mixed well.   
  • Chemically treated water is sometimes not very palatable.  This can be resolved by adding a pinch of salt per quart of water or add flavorings such as Tang, lemonade mix, gatorade powder, etc. Sometimes pouring the water back and forth between containers will help with the flavor.  

Common chemicals used for purification/disinfection

  • Chlorine

Chlorine has been widely used and accepted as a safe and effective means of water disinfection since it became popular in the 1920’s.

It is effective against a wide range of bacteria, viruses, and cysts. 

Chlorine comes in a variety of formulations including liquid, tablets, and granules. Chlorine needs to be handled carefully.  It can easily cause skin and respiratory irritation. The tablets are actually highly flammable.  If mixed with acids or other chemicals, it is potentially highly explosive.

It is readily available in the form of household bleach. It is formulated with different base agents such as calcium hypochlorite and sodium hypochlorite.  Household bleach ranges from 5.25 to 8.25 percent chlorine.  Avoid using bleach with additives such as perfumes and dyes. 

One disadvantage to using chlorine is that it introduces a strong taste and odor to the water, especially household bleach. Many people find the water to be unpalatable. This is the primary reason for most people not consuming chlorinated water even in an emergency situation.  However, the undesirable taste can be resolved easily by adding powdered drink mixes.  

To treat water with household bleach containing 5.25 to 8.25% chlorine: 

  • 1 quart/1liter: 5 drops
  • 1/2 gallon/2 quarts/2 liters: 10 drops
  • 1 gallon: 1/4 teaspoon
  • 5 gallons: 1 teaspoon (about 5 milliliters)
  • 10 gallons: 2 teaspoons (about 10 milliliters) 


  • Chlorine Dioxide

The development of Chlorine Dioxide as a potential means of water purification is relatively new. Consequently, it is important to read all product information carefully.  This product come in two forms: tablets and two part liquids.  

There are two disadvantages to using this product. The tablet form is expensive compared to other products.  The liquid product requires the mixture of two separate components which then needs to sit for a specific amount of time prior to use.  Consequently, this application may have limited use in emergency situations.  

  • Iodine

Iodine has long been used as a means of water purification.  It is effective against most bacteria, viruses, and protozoal cysts. It is more effective than Chlorine for neutralizing Giardia cysts. If used for the inactivation of Giardia, the water temperature should be at least 68 Degrees F (21 C)  If the water is not clear, you need to use a higher concentration of Iodine.  

Iodine causes a yellow discoloration to the water and produces an odor and taste that many people find unpalatable. After the water is treated, you can use a neutralizer tablet to counteract the taste with the resulting water being more palatable. Another trick is to add about 50 milligrams of vitamin C to the iodized water, which will eliminate any taste or color of iodine. (The vitamin C in Tang drink mix also works well.) 

For liquid 2% tincture of Iodine, add 5 drops per quart of water if the water is clear.  Add 10 drops per quart of water if the water if cloudy.  

CAUTION: There are a number of studies that have linked significant side effects and health risks associated with exposure to Iodine. Some people are allergic to Iodine.  Any person with thyroid problems, women over 50 years old, pregnant women, or persons on lithium should consult their physician prior to using iodine products.  

  • NaDCC

Sodium Dichloroisocyanurte (NaDCC) has become one of the most popular means of water purification.  The properties of NaDCC are dramatically different from chlorine. It is safe to handle, completely stable and inert in the tablet form. 

When added to water the tablet dissolves and releases a specific dose of hypochlorous acid or free available chlorine. This produces a safe and effective water disinfectant.  It is available in a range of tablet sizes. Each tablet is formulated to treat a specific volume of water, ranging from 1.0 L to 2500 L.  It can be used to prevent cholera, typhoid, dysentery, and other water borne diseases. It is also effective against Giardia when used as directed.  

NaDCC truly provides the best of both worlds. It has the effectiveness of chlorine without the strong taste and odor. (It does produce a slight chlorine taste.) It is comparable with Iodine as far as its effectiveness against bacteria, viruses, and cysts. But, unlike Iodine, it does not produce an unpleasant taste or odor and has no adverse health affects. Additionally, the tablets have a very long shelf life, approximately 4 to 5 years.

I purchased this product from a company off of eBay.  It was very reasonably priced. I keep several hundred tablets on hand as a back up to my filtration system. Additionally, if you are simply filtering water, that water could then be treated with this product and placed in long-term storage.       

Drinking raw water

As a general rule, never, never, never, never, drink water unless you know it is safe. 

Acquiring an intestinal pathogen from drinking unprocessed water can result in intractable (incurable without medication) diarrhea. That will result in extreme dehydration in a short period of time.  This is not something you want to risk unless your life depends on it. If you are in an extreme survival situation, have absolutely no choice, and it means the difference between life and death, then take the risk and drink the water anyway.   

According to the World Health Organization and UNICEF,  on a global basis, over 6,000  people die every day from diarrhea.  Most of this can be prevented by simply having access to a safe water supply.  

Do you really want to risk your life by simply NOT planning ahead. 

Take Home Message

I have lived off the grid for over 20 years. One of the things that helps to ensure my independence is having safe water supply. 

My water actually comes from a local stream.  I pump water into a truck mounted tank. Some of the water is chlorinated and transferred into a 525 gallon under ground cistern. That water is used for showers, cleaning, washing dishes,, etc.  It is also used for the livestock (chickens, turkeys, etc). 

Raw stream water is also filtered for drinking.

The table top filter, which is a drip system, is two 5 gallons buckets. The top bucket has two Berkey filters. However, this is a slow drip and it takes about 12 hours to produce 5 gallons of drinking water. 

The second system, which is much more efficient, is a product by LifeStraw. It filters 12 liters of water and less than two hours. This product is commonly used in disaster scenarios because it is a fast way to produce a large amount of safe drinking water. My system hangs in the shower.

The take home message is that I produce safe drinking water for less than three cents per gallon.  My investment in equipment was less than $200 USD. 

If I can do this while living off the grid, then every person connected to a public infrastructure has no excuse for not constantly maintaining a safe water supply. It is simple to do.  At the risk of sounding overly dramatic, it may one day make the difference between life and death.  

Other posts of interest

How to Choose the Best Water Filter

The Ten Essentials Needed for Survival

14 Ways to Cook Without Using Your Kitchen Stove

Go off grid and live well,  


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