Seven Ways to Purify Water

by Dr. David Williams

Clearing up the confusion about methods and products

Water is one of the few substances that you put into your body every day of your life. Weeks, months or even a lifetime of drinking so-called “safe” or “approved” water could prove to be one of your biggest health risks.

Even “approved” drinking water under the Environmental Protection Agency (EPA) standards, may contain specified amounts of lead, arsenic, mercury, radioactive particles and a long list of other poisons. All of which have been shown to accumulate in body tissue over time, leading to illness and even death.

There’s a lot of confusion and misinformation out there on methods and products being used to clean drinking water. I’ll try to clear up some of that confusion and give you an overview of current water purification methods for both home and industry. Plus, I’ll show you how to determine which method or methods are best for you.

1. Carbon Filters Pros:

  • Great for removing pesticides and chlorine
  • Inexpensive

Filters come in all shapes and sizes. They’re one of the oldest and least expensive options for purifying water. Carbon has always been the most popular filtering medium, and probably more work has been done on tweaking and adapting carbon for filtration purposes than on any other medium.

Most carbon filters utilize a special form of carbon called activated carbon. Water easily passes through an activated carbon filter, which provides an almost unbelievably large surface area (125 acres per pound). Activated carbon is used in both the solid block and granular forms. It takes water longer to pass through block carbon, which makes this form more effective at absorbing contaminants.

Activated carbon filters are best suited for removing organic pollutants like insecticides, herbicides and PCB’s. They can also remove many industrial chemicals and chlorine. Activated carbon will not remove most inorganic chemicals, dissolved heavy metals (like lead) or biological contaminants. To help overcome these weaknesses, many manufacturers use activated carbon in conjunction with other processes, such as ceramic filters or ultraviolet light, as I’ll discuss later on. Even with these additions, however, carbon filtration systems have their limitations and drawbacks.


  • Does nothing against bacteria
  • Not long-lasting

Carbon filters provide a fertile breeding ground for bacteria. If water hasn’t been treated with chlorine, ozone or some other bactericidal method before undergoing carbon filtration, any bacteria in the water will become trapped inside the filter and further contaminate the water that runs through it. For this reason, I would not recommend using a carbon filter alone if your water comes from an unchlorinated well. Some manufacturers will claim that the problem can be taken care of by impregnating the carbon material with silver. Unfortunately, this doesn’t work. The water must remain in contact with the silver for much longer than what actually occurs.

Carbon filters also begin to lose their effectiveness over time. As the filter reaches its absorption capacity, more and more impurities will be left in the water. And since the water will continue to flow easily through the filter, there is no true way of knowing if the filter is still functioning properly without running a water quality test. This makes it essential that the filter be changed at regular intervals or when its water filtration capacity has been reached, whichever comes first.

2. Ceramic Filters Pros:

  • Great against parasites and physical impurities
  • Easy to clean

Rust, dirt, parasites like Cryptosporidium and Giardia lamblia, and other impurities can be easily removed from drinking water by forcing the water through the very fine pores in ceramic material. Some breweries use ceramic filters as an alternative to pasteurization. They’re also ideal for travel or backpacking, since they can be repeatedly cleaned by simply scrubbing the outside of the ceramic material.


  • Ineffective against organic pollutants and pesticides

Ceramic filters, however, are not effective at removing organic pollutants or pesticides. For home drinking water, I cannot recommend them on their own. They need to be paired with a carbon filter.

3. Ozone Pros:

  • Kills bacteria, viruses, algae and parasites

Ozone (O3) differs from normal oxygen in that it contains three atoms of oxygen instead of just two. This extra oxygen atom makes it highly unstable and reactive. When ozone gas bubbles through water, it quickly and very efficiently kills bacteria, viruses, algae and parasites. Not only is it thousands of times more potent than chlorine, it doesn’t produce any harmful by-products like chlorine does. For these reasons it has become a viable method to treat water in swimming pools and spas.


  • Ineffective against heavy metals, minerals and pesticides
  • Effectiveness dissipates quickly
  • Prohibitively expensive

For drinking water, however, ozone alone does not offer a total solution. It does not remove heavy metals, minerals or pesticides. And unlike chlorine, which remains in the water and continues to work, ozone has a very short “half-life.” In other words, it dissipates almost instantly and offers no residual purifying power. The final stumbling block with ozone filters is availability and price. I don’t know of any commercial ozone product that could be used economically to purify home drinking water.

4. Ultraviolet Light (UV) Light Pros:

  • Kills bacteria and viruses

When microorganisms like bacteria and viruses absorb UV light, certain chemical reactions are triggered which kill the organism. This makes it a very efficient method of destroying pathogens like E. coli and salmonella without having to add chemicals like chlorine. UV light is one of the few purification methods that gets out viruses, which is particularly important if you live in a rural community or have well water.


  • Not effective against all organisms
  • No effect on heavy metals, pesticides, or other physical contaminants

However, UV light has its drawbacks: It is not effective at killing all types of organisms (such as certain parasites), and it has no effect on heavy metals, pesticides or other contaminants. For UV to be effective, the treated water must be exposed to the light source for an adequate period of time. Finally, the water must be relatively clear to begin with for the light to be able to penetrate. Like most methods, UV light alone is not enough, and should be considered an adjunct to other treatment forms.

5. Ion Exchange Systems Pros:

  • Prolongs water heater


  • Doesn’t have any effect on water purity or your health

“Ion exchange system” is a $100 phrase that refers to nothing more than a water softener. Softening hard water may improve your laundry and prolong the life of your hot water heater, but it won’t do anything to prolong your life. Water softeners don’t purify water.

6. Copper-Zinc Systems Pros:

  • Effectively removes chlorine, heavy metals

Another form of water filtration technology, being sold under the name KDF, uses granules of copper and zinc alloy to purify water. The copper and zinc molecules act like the different poles on a battery. As contaminated water passes through the granules, certain contaminants are drawn toward the zinc while others with a different charge migrate to the copper. Additional chemical reactions take place which release ozone and other compounds that kill bacteria and other organisms.

KDF filtration effectively removes chlorine and its by-products, as well as heavy metals.


  • Ineffective against pesticides and organic contaminants

Copper and zinc filtration technology cannot remove pesticides and other organic contaminants. However, KDF systems usually incorporate precarbon block filters to make up for these shortfalls.

7. Reverse Osmosis Pros:

  • Highly effective against metals, bacteria, viruses, organisms, and organic and inorganic chemicals

Reverse osmosis (RO) is a process whereby water is forced through a semipermeable synthetic membrane. It was originally used to transform saltwater into freshwater. Under the right conditions, RO systems can remove anywhere from 90% to 98% of heavy metals, viruses, bacteria and other organisms, organic and inorganic chemicals.


  • Wastes lots of water
  • Synthetic membrane degrades when exposed to chloride and physical contaminants
  • Systems can breed bacteria, requiring a carbon filter in between RO treatment and storage
  • Does not work well with hard water

RO systems have several significant drawbacks. For starters, they’re extremely resource intensive and wasteful; for every gallon of pure water produced, between three and eight additional gallons of water get washed down the drain. The fact that this waste (or wasted) water contains concentrated contaminants has led many communities suffering from a lack of water to ban RO systems altogether.

These systems also require a minimum water pressure of 40 psi to work properly, and steps must be taken to insure the integrity of the membrane, which has to be replaced every few years. The membrane will also degrade in the presence of chlorine and turbid water. This makes a carbon prefilter essential.

RO systems have also come under attack for being ideal breeding grounds for bacteria, which can necessitate installing another carbon filter between the RO unit and the water storage tank, and a third filter between the storage tank and the water outlet.

Finally, if your water is hard you may need to use a water softener prior to running it through the RO unit.

Considering these limitations, I really don’t consider reverse osmosis the best way to go.

The Best: Distillation

When used correctly, distillation provides the purest and safest water available. There are critics of distillation, but I think it is the very best way to go when it comes to all-around water purification. I’ve used it in my home and office for years.

Distillation is a fairly simple process. Water is heated until it boils and turns to steam. The boiling action kills the various bacteria and other pathogens, and as the steam rises it leaves behind waste material, minerals, heavy metals and other heavier contaminants. The steam is then cooled and returns to water.

A very similar process occurs millions of times daily all over the planet. Ground water evaporates and rises in a purified form into the atmosphere, where it accumulates and eventually returns to earth as rain or other forms of precipitation. Back when our atmosphere wasn’t contaminated, rain was pure and clean, much like the distilled water you can make in your home today.



0 #2 Judi Flanders 2012-09-08 12:04
Wonderful information that is important to out health.
0 #1 Paula Marlatt 2012-08-25 14:35

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