| water is essential to our health and comfort. Not only | | | | Reverse osmosis, also known as hyperfiltration or |
| do we rely on it to stay hydrated, we use it in many | | | | ultra-filtration, was developed with U.S. government |
| other ways including bathing, cleaning and cooking | | | | funding as a means of desalinating ocean water. A |
| food, and laundering our clothes. Fresh water has long | | | | reverse osmosis water purifier uses a |
| been a concern of both public communities and | | | | semi-permeable membrane that allows pure water to |
| private individuals, and several different water | | | | pass through it, while contaminants are trapped by |
| purification systems and treatment technologies have | | | | the tiny pores in the membrane. |
| been developed to help ensure that tap water is | | | | The process requires that the water be pressurized |
| safe for human consumption. But how do these | | | | to help force it through the membrane. Most |
| different technologies compare? | | | | standard residential water systems have sufficient |
| Whether you get your water from a well or a city | | | | pressure. Like activated carbon filters, reverse |
| system, water sources can become contaminated by | | | | osmosis also uses charged particles to help filter out |
| bacteria, runoff, and improper treatment. Even if | | | | impurities. |
| water isn’t contaminated, it may contain iron | | | | The effectiveness of a reverse osmosis water |
| and other hard minerals that cause discoloration and | | | | purifier depends on the density of the membrane. A |
| can build up in the body, or chlorine that leaves an | | | | membrane with larger pores will obviously let larger |
| unpleasant odor and taste. Consequently, many | | | | impurities pass through. It is also important that the |
| people choose to treat or filter their water to | | | | membrane be cleaned regularly for proper functioning. |
| improve flavor and protect against contaminants. | | | | Higher quality reverse osmosis water filters use a |
| Chlorine is commonly used by municipal water | | | | process known as crossflow to allow the membrane |
| treatment plants and is effective in killing many | | | | to continually clean itself. Crossflow directs some of |
| different bacteria. However, it is not effective against | | | | the water downstream from the membrane, |
| some organisms such as Cryposporidium and Giardia. | | | | sweeping the rejected contaminants away so they |
| Both of these organisms can be found in lakes, | | | | do not build up and block the membrane. |
| rivers, and ground water and can cause serious | | | | There are two types of membranes commonly used |
| intestinal illness. | | | | in reverse osmosis water filters --Thin Film Composite |
| As mentioned, many people feel that chlorine leaves | | | | (TFC) and Cellulose Triacetate (CTA). TFC |
| an unpleasant taste and smell. In addition, there have | | | | membranes are noticeably more effective the CTA |
| been numerous cases where the city water supply | | | | membranes but they tend to be less resistant to the |
| became contaminated despite the fact that it was | | | | deteriorating effects of chlorine. This problem can be |
| treated. People with city water supplies often use | | | | avoided by using an activated carbon pre-filter to |
| other water purifiers and home water filters to | | | | remove the chlorine first. |
| ensure that their water is pure and tastes good. The | | | | Reverse osmosis water purifiers come in different |
| three most common options are carbon filters, | | | | sizes and styles including countertop and whole house |
| reverse osmosis water filters, and ultraviolet light | | | | water purification systems. They are capable of |
| water purification. | | | | filtering out a long list of contaminants including: |
| Each of these technologies uses a different approach | | | | • chlorine and other treatment related |
| to treat water, and they each have different levels | | | | products |
| of effectiveness against various contaminants. One | | | | • bacteria |
| may work well to remove chemicals but be | | | | • salts, sugars, proteins |
| completely ineffective against bacteria, and vice | | | | • dyes |
| versa. | | | | • heavy metals |
| In reality, there is no single filter or treatment that | | | | One drawback of reverse osmosis water filters is |
| will eliminate every contaminant from your water. | | | | that they are more expensive than carbon filter |
| The best approach is to have your water tested for | | | | treatment systems, with the average home system |
| contaminants and then purchase a home water | | | | costing around $300. Also, the purification process is |
| purifier that guards against the particular | | | | usually somewhat slow due to the use of pressurized |
| contaminants that cause you concern. | | | | water. It can take an entire day to produce 15 |
| Another option is to combine treatment technologies. | | | | gallons of purified water. And a typical reverse |
| Most higher-end systems use a combination of | | | | osmosis water purifier may need up to 8 gallons of |
| carbon filters and one of the other treatment | | | | untreated water to generate a single gallon of |
| technologies to achieve the best results. Let’s | | | | purified water. |
| look at the different technologies to see where each | | | | UV Water Purification |
| is effective. | | | | As the name implies, ultraviolet light water purification |
| Carbon Filters | | | | systems use ultraviolet (UV) light to treat water and |
| Carbon is one of the most powerful absorbents | | | | render microorganisms harmless. The UV light comes |
| available and it has been used for many years as a | | | | from a high intensity lamp that is usually enclosed in a |
| means of removing impurities. The absorbing powers | | | | protective quartz sleeve. When water passes |
| of carbon can be further enhanced by adding a | | | | through the water treatment system, the UV light |
| slightly positive electrical charge. This is known as | | | | damages the structure of any organisms and makes |
| activated carbon, and it is used in many standard | | | | them sterile. |
| home water filters. As the water passes over the | | | | Although a UV water purifier requires electricity to |
| positively charged carbon, the negative ions of the | | | | operate, it draws about the same amount of energy |
| contaminants are drawn to the surface of the carbon | | | | as a light bulb. However, the lamp bulb itself needs to |
| granules and removed from the water. | | | | be replaced every year to ensure adequate intensity. |
| Activated carbon filters typically use granular | | | | While whole house UV water purification systems are |
| activated carbon (GAC) or powdered block carbon. | | | | effective on most bacteria, viruses, molds, algae and |
| Both work well for filtering and purifying but carbon | | | | other organisms, they do not remove chlorine, heavy |
| block filters have been shown to remove more | | | | metals, VOCs, or other chemicals. And countertop |
| contaminants. Either type of activated carbon filters | | | | UV systems, which expose the water to UV lighting |
| help reduce or remove a wide variety of | | | | for less time, do not always remove all organisms. |
| contaminants, including: | | | | UV water purifiers average around $700 for a whole |
| • volatile organic chemicals (VOCs) | | | | house system, making them more expensive initially |
| • pesticides and herbicides | | | | than other types of treatments. In addition, without |
| • chlorine, radon, and other chemicals often | | | | a pre-filter system, contaminants can build up and |
| found in tap water. | | | | reduce the intensity of the UV lamp. For these |
| All of this protection comes in a relatively inexpensive | | | | reasons, many people combine UV water purification |
| package. You can purchase carbon filter systems | | | | systems with carbon filters, which also increases the |
| that fit on your faucet for about $30, or you can | | | | costs. |
| choose a whole house water purification system that | | | | As you can see, each of the three common water |
| utilizes carbon filter technology for around $100. | | | | treatment technologies has its advantages and |
| However, unless they are densely compacted, most | | | | drawbacks. Deciding which is best depends on your |
| carbon block filters are not effective at removing | | | | budget and the type of water contaminants you |
| heavy metals or bacteria. For this reason, many | | | | want to remove or prevent. A test of your tap |
| people consider combining carbon filters with one of | | | | water will help you determine the appropriate water |
| the other types of water purification systems. | | | | filtration system for your needs. |
| Reverse Osmosis Water Filters | | | | |