What follows is what I think are the ten most significant methods of treating water. This is my opinion, but I am sure some people are going to disagree with me and say I left something out. Feel free to do so. The Top 10 Methods are in no particular order, so one is not more dominant than another.

1. BOILING Lets start with the most basic. In an emergency, boiling can disinfect your water in a pinch that is unsafe because of parasites or bacteria. If the water is cloudy, it should be filtered before boiling. It can be filtered easily with coffee filters, paper or cotton towels, cheesecloth, or anything of the like to remove the cloudiness. Pour the water in a clean container and bring it to a full boil for at least 3 minutes. Covering the container will help reduce evaporation. If you are more than 5,000 feet above sea level, you must increase the boiling time to at least 5 minutes (plus about a minute for every additional 1,000 feet). Keep the boiled water covered while cooling. The benefits of boiling water are that pathogens and parasites that may be lurking in your water will be killed if the water is boiled long enough, making it safe to drink, but because of the inconvenience, boiling water is not widely used, unless an emergency rises. The biggest disadvantage with boiling water is of coarse you will need an energy source. Meaning if a stove-top is not available, a fire will need to be lit. And boiling is not effective against toxic chemicals like lead, mercury, asbestos, pesticides, solvents, etc, or if nitrates have contaminated the water. As science and technology has advanced, many different treatments and water systems have emerged. Here are the best and most common.

2. DISTILLATION Think of distillation as the opposite of boiling. The water is usually boiled in a chamber causing it to vaporize into steam. With the contaminants behind, the steam moves to a different part of the unit and cools until it reverts back into liquid water and moves into a storage container. A good distillation unit produces very pure water and is one of the few practical ways to remove nitrates, chloride, and other salts. Distillation also removes pathogens in the water by killing and leaving them behind when the water vapor evaporates. As long as the distiller is kept clean and working properly the high quality of treated water will be very consistent with no drop in quality overtime; plus no filter cartridges to replace, unless a carbon filter is used to remove volatile organic compounds. The disadvantages of Distillation is that it can take two to five hours to make a gallon of distilled water, and to produce water effectively, there is required periodic cleaning of the boiler, condensation compartment, and storage tank. The cost of ownership is high because after the initial cost of the unit and you also must pay for the electrical energy for each gallon of water produced. If it costs you $0.25 to distill each gallon, and you purified 10 gallons per week, you wouldpay $130 for your 520 gallons of distilled water each year. Also, don't forget this: because most distillation units require electricity, it will not function in an emergency situation when electrical power is not available.

3. Reverse Osmosis (RO): RO's have become one of the more popular drinking water treatments found in today's homes. Water pressure is used to force water through a membrane, leaving the larger contaminants behind. Purified water is collected, and water containing the contaminants is flushed down the drain. The average reverse osmosis system is a unit consisting of a sediment/chlorine pre filter, the reverse-osmosis membrane, a water storage tank, and an activated-carbon post filter. They cost from about $150 to over $1,500 for point of use systems.

The Good: Reverse osmosis significantly reduces salt, inorganic material present in the water, and some organic compounds. Microscopic parasites (including viruses) are usually removed by properly functioning reverse osmosis units. RO systems can typically purify more water per day than distillers and are less expensive to operate and maintain. Reverse Osmosis systems also do not use electricity, although because they require relatively high water pressure to operate, they may not work well in some emergency situations.

The Bad: Reverse osmosis systems waste some water. Two to four gallons of "waste" water are flushed downthe drain for each gallon of filtered water produced. While reverse osmosis is highly effective, depending on your filters, some pesticides, solvents and other volatile organic chemicals are not completely removed by reverse osmosis. A good activated carbon post filter is recommended to reduce these contaminants. Although RO's do not use electricity, they depend on a relatively high water pressure to force the water molecules through the membrane. In an emergency situation where water pressure has been lost, these systems will not function. And finally, RO systems require maintenance. The pre and post filters and the reverse osmosis membranes must be changed according to the manufacturer's recommendation, and the storage tank must be cleaned periodically.

4. Water Filters: The topic of water filters is complicated because there are so many models available (over 2,500 different models manufactured by more than 500 companies), and because there are so many types of filtration strategies and combinations of strategies used. The basic concept behind nearly all filters, however, is fairly simple. The contaminants are physically prevented from moving through the filter either by screening them out with very small pores and/or, in the case of carbon filters, by trapping them within the filter matrix through attracting them to the surface of carbon particles (the process of adsorption). There are two main types of filter, sediment, which strains out unwanted particles, and activated carbon, which absorbs and traps them. Sometimes they are combined into a single unit.

The Good: A benefit of all home filtration systems is that they require no electricity to filter the water, as normal home water pressure is used to force the water though the filter. The only routine maintenance required is periodic replacement of the filtration element. As long as the cost of the replacement filter elements is reasonable (depending on the type), owning even a high-end water filter can be very inexpensive if you look at the long term costs and compare itwith other solutions.

The Bad: Viruses can not be effectively removed by any filtration method alone. And it's important to remember there are several different kinds of filters, all with there own limitations. Just a few examples: “GAC” Carbon filters can never have hot water run through them and are not effective at killing bacteria. And other filters can not remove containiments like Chlorine, lead, and mercury. It's important to talk to a water specialists or do your own research to see which filters will best battle your specific needs.

5. Bottled Water: Did the water in the bottle you just purchased really come from the beautiful spring shown on the label? Bottled water can have minimal (or no) processing - as in natural spring or mineral water, or it can be completely filtered and demineralized to nearly pure water and then have minerals added back in to make it taste better. The bottled water industry would like you to believe that it is safer and better than tap water, but that really depends on the bottling company. High quality in-home water treatment systems can have the same if not better quality water as bottled water.

The Good: Bottled water can be an emergency source of water in the event your primary water source fails orbecomes contaminated. It's a convenient source of safe water for drinking outside of the home, and since it does not contain chlorine, it may taste better than untreated tap water. Most bottled water will contain fewer contaminants than untreated tap water.

The Bad: Many of us are willing to pay extraordinary prices for the availability and convenience of certain products. That 16 ounce bottle of "designer water" you just purchased at the gas station for 99 cents, costs $8.00 per gallon, probably more than twice as much per gallon as your gas! Purchasing one 16 oz bottle per day (at $0.69 per bottle) will cost you $365 per year - that's for a total of 45 gallons. If you were to take a minute to fill your own well-cleaned bottle with filtered or distilled water, however, a 16 oz bottle of water would cost maybe a penny!

The Ugly: Producing bottles uses resources (for every 16 oz plastic bottle, it could be filled with 3 inches of gasoline, representing how much it took to produce it.) and unless they are reused or recycled, they cause a waste disposal problem. Transporting bottles of water from the bottler to stores or homes also uses resources.

6. Ultraviolet Light: Water passes through a clear chamber where it is exposed to Ultraviolet (UV) Light. UV light effectively destroys bacteria and viruses. Ultraviolet is typically used as a final purification stage on some filtration systems. If you are concerned about removing contaminants in addition to bacteria and viruses, you would still need to use a quality carbon filter or reverse osmosis system in addition to the UV system.

The Good: No chemicals are used in treating the water and ultraviolet leaves less of a carbon footprint .It removes some organic contaminants while leaving no smell or taste in the treated water. Ultraviolet light requires very little contact time (seconds versus minutes for chemical disinfection), improves the taste of water, microorganisms and pathogens are destroyed, and it does not affect minerals in water.

The Bad:UV radiation is not effective for water with high levels of suspended solids, turbidity, color, or soluble organic matter as these materials can react with UV radiation, and reduce disinfection performance. Ultraviolet light is not effective against any non-living contaminant like, lead, asbestos, many organic chemicals, chlorine, etc. Ultraviolet light requires electricity to operate. In an emergency situation when the power is out, the purification will not work.

7. Water Softeners: Very popular systems used to remove the unwanted effects of hard water. In this process, water passes through a media bed, usually sulfonated polystyrene beads. The beads are supersaturated with sodium, a positive ion. The ion exchange process takes place as hard water passes through the softening material. The hardness minerals (positively charged Calcium and Magnesium ions) attach themselves to the resin beads while sodium on the resin beads is released simultaneously into the water. When the resin becomes saturated with calcium and magnesium, it must be recharged by passing through a concentrated salt brine

The Good: The nuisance factor of hard water is reduced. It will make your plumbing last years longer and your laundry become whiter and brighter. In the long run you will also save money on detergent as less soap is used to clean your clothes.

The Bad: The process of regenerating a water softener dumps salt water into theenvironment.The elevated sodium concentration of most softened water can affect the taste and may not be good for people on low sodium diets, although sodium concentrations are typically quite low relative to sodium levels in most food. The process does not reduce the level of biological contaminants (bacteria, viruses, cysts), nor does the process reduce the levels of most organic compounds. Typically, approximately 50 gallons of rinse water per cubic foot of resin isrequired to totally remove hardness and excess salt from the resin after each regeneration. Softened water is not recommended for watering plants, lawns, and gardens due to its elevated sodium content.

8. Salt Free Water Conditioners: Newer to the market, Water Conditioners are the “Green” alternative to Water Softeners. The water is treated without the need for salt. Rather than attempting to prevent hard water by removing or adding chemicals, water conditioners redirect and suspend the scale in the water.

The Good: Because there is no need for salt, a Water Conditioner will save you money immediately versus a Water Softener. No salt also means much less of an impact on the environment.

The Bad: Despite what some companies may claim, salt free systems do not soften the water, as it is impossible without removing the minerals. Like water softeners, salt-free water conditioners will not remove bacteria or harmful chemicals alone (they work rather as a pretreatment for a water purification system.)

9. Ozonation:Ozone systems have long been in use in Europe and over the past twenty years it is also becoming more commonplace in America. Ozonation is a water treatment process that destroys bacteria and other microorganisms through an infusion of ozone, a gas produced by subjecting oxygen molecules to high electrical voltage.

The Good: Ozonation has a low operating cost and provides an additional barrier to protect public health and enhances water quality. Ozonation is very effective for destroying or inactivating viruses and bacteria, as well as Cryptosporidium and Giardia. Additionally, it reduces the formation of chlorinated disinfection byproducts such as trihalomethanes (THMs) and haloacetic acids (HAAs), which result from the interaction of chlorine and naturally-occurring organic material in the source water and provides improved taste and odor control in water supplies.

The Bad: Ozonation generally has a high initial cost, which some feel makes it cost prohibitive.

10. Chlorination & Oxidation: These are not mutually exclusive. Chlorine a good disinfectant, but not a good oxidizer like Ozone, Hydrogen Peroxide or Oxygen. Chlorination was responsible for eradicating cholera and typhoid in the US. Chlorine is used for killing bacteria. Hydrogen Peroxide is a better oxidizer, but not as good of a disinfectant. Ozone is a stronger oxidizer than either one and also a good disinfectant. That's my Top 10 - Do you have one that I've left off the list?