Filtration Equation: Water Filter Solutions

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Consider a water filter if someone in your family is highly susceptible to illness.
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Whole-house water filter systems, such as this one from LifeSource, filter both hot and cold water.
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The EcoWater Systems ERO 375 series has an electronic monitoring system to tell you when it’s time to change filters.
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Brita offers popular over-the-faucet filters.
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The Waterwise 8800 steam distiller

Only 39 percent of Americans think their water is “as safe as it should be,” according to a 2008 survey by the Water Quality Association, a nonprofit trade association. They’re worried about pharmaceuticals, solvents, rocket fuel, plasticizers and hormones, not to mention lead from old pipes and chlorine from water treatment plants. Even those who aren’t worried about their health may think their water has an off taste or a bad smell, or find stains on laundry and plumbing fixtures.

In truth, the United States has some of the world’s best water-treatment facilities–most of our tap water is safe. But in some situations, home water filtration can make a difference.

You might consider a filter if:

? You or someone in your family is highly susceptible to illness (infants, the elderly or those with compromised immune systems).

? You get your water from a spring, well or untreated source.

? Stains or mineral deposits form on plumbing and discolor laundry.

? Your water has an unpleasant taste or smell.

? You have a known problem with your water quality.

It’s important to choose the best filtration system for your needs–you’ll want to do some homework before making a purchase. There’s no perfect, one-size-fits-all technology, says Rick Andrew, operations manager at NSF International, a third-party certifier of water filters. Answering the following questions can help you determine whether you need a filter and, if so, which one best meets your needs.

What’s in the water?

First, become educated about your water supply. Public utilities are required to provide annual Consumer Confidence Reports (CCR) or Right-to-Know Reports that reveal your water supply source and include a rundown of contaminants and how they are treated. The CCR has definite shortcomings: It shows only average contamination levels; it includes only the hazards it’s required to list; and it may ignore substances such as chlorine used in the treatment process. Plus, the report can’t say if the water at your tap is safe; from the treatment facility to your faucet, lead, radon, arsenic or other hazards–some naturally occurring–can enter water. Luckily, you can easily test your water with an inexpensive at-home kit (available at hardware stores), or hire a professional to do it. The local health department may even provide a test for free. If you have a well or spring, test annually.

What is the risk?

Once you’ve learned what con-taminants are present in your water, learn more about any potential risks they pose. The Environmental Protection Agency has established acceptable levels for many common water quality hazards, but many states have set even more stringent requirements. The NSF provides a comprehensive database of common contaminants, their known health risks, and the acceptable levels.

While pure water is often used as a marketing ploy, the reality is that water is not pure, and the minerals in it are natural. In fact, Andrew points out that some substances in water, including magnesium and calcium, are beneficial, and highly purified distilled water tastes flat to most people.

Don’t get a water filter if you don’t really need one. “If you don’t have contaminants at a level that’s a concern and you’re OK with the taste, you really don’t need any kind of filtration,” Andrew says. “There are a great number of consumers who are perfectly satisfied with their water.”

There’s an environmental cost associated with every kind of filter. For example, reverse osmosis filters consume more water than they create, and some distillation filters lose water in the process. Many water softeners add unwanted minerals to the wastewater; in some areas with salinity problems, softeners are banned. All filters require natural resources and energy, either at the point of use (in your home) or during manufacture and transport.

Which filter should I buy?

If you find that any contaminants are at higher-than-acceptable levels, or if the water is of good quality but the smell, taste, rust stains or laundry discoloration are problems, a filter could help. It can also offer protection against pathogens for those with compromised immune systems.

Matching the filter to the concern is the No. 1 consideration in choosing a filter, Andrew says. Learn which filtration method might be most effective at removing your particular problem. The NSF Contaminant Guide is a terrific place to start. You also can search its database of certified filters by brand or keyword.

Consider the filter style that might work best for your situation: pitcher, fridge-door, sink-mount, showerhead, whole-house or a combination. Do you just want a quart or two a day for drinking? Or do you have a large family? And do you need to treat water for washing clothes and household use, as well as for drinking?

Think long-term. Will you change the filters or perform necessary maintenance, or are the tasks too time-consuming and the components too expensive? Neglect of required maintenance is a major cause of system failure.

Water Filter Types

You can purchase one type only or a hybrid system.

Absorption/Filtration, or Carbon

Among the least-expensive methods, carbon filters are great for removing foul tastes and odors, but they become less effective with time and must be changed frequently. Pitchers, refrigerators, bottle-top and sink-mount types are usually carbon filters.

“Some [carbon filters] do a lot more than just take care of taste and odor problems,” Andrew says. “Some are certified to remove more than 20 different contaminants–like organic contaminants, particulate matter, heavy metals and pesticides–so there’s quite a broad range.”

Many carbon filtration systems also use KDF (kinetic degradation fluxion) technology, in which copper and zinc neutralize chlorine and its byproducts, as well as remove heavy metals. KDF technology helps extend a carbon filter’s life and may reduce mineral deposit buildup.

Water Softener/Exchange System

A softener removes calcium and magnesium ions, which cause “hardness” or mineral deposits, and replaces them with sodium and potassium ions. One benefit is that soft water requires less detergent, which “is always a green thing,” Andrew says. A softener is a poor choice for those on diets that restrict potassium or sodium, and they are banned in some places because they add salinity to wastewater.

Reverse Osmosis (RO)

In RO systems, water is forced through a semipermeable membrane that blocks contaminants. The process removes dissolved metals and dissolved ions that are unaffected by carbon-type filters, but it is very slow–water is held in an accumulator tank until it is used–and consumes several times as much water as it filters.

If you or someone in your family has a health issue, especially a compromised immune system, you may want to consider reverse osmosis. RO filters remove Crypto (Cryptosporidium parvum), a parasitic microorganism that is highly resistant to conventional disinfection methods (except boiling). Water-treatment facilities, which use chlorine, may not control Crypto effectively. (For more information, contact your local health department or visit

Ultraviolet (UV)

UV light disinfects, removing microorganisms such as bacteria, viruses and protozoa. Most home UV systems are point-of-entry, meaning they treat all water coming into the home, although a few are now point-of-use at the sink or refrigerator. The drawback is that they cost several hundred to several thousand dollars, and most continuously consume electricity–at about the rate of an energy-efficient refrigerator.


If you have very poor water quality, distillation is a good solution, Andrew says. The downside is that the method consumes a lot of energy to heat water to a vapor then condense it again. Additionally, distillation loses some water to evaporation.

Alternative distillation systems, most often used in rural areas of the Southwest, rely upon solar power to heat and vaporize the water. Also, researchers are developing new technology that would reuse the steam to heat household water, so the energy efficiency may improve.

Ozone or Ozonation

Ozone filters use O3, a natural disinfector, to remove contaminants from water. The third oxygen molecule is unstable, so it binds with other chemicals, which then can be filtered out of water more easily. The flip side is that this process can sometimes create unwanted byproducts, such as formaldehyde and bromates. For this reason, filtration systems must rely on an additional filter to purify the oxidized product. As they are also expensive to install and operate, some experts do not recommend purchasing an ozone filter.


It’s still the best way to remove micro- organisms such as Crypto–and boiling is recommended when water-treatment systems are breached. But it also requires time and energy. If you have a temporary or occasional need for sanitized water, boiling for at least one minute will work–but avoid this method as a long-term fix.

Water-Filtration Types

Absorption/Filtration, Carbon
Pros: Removes undesirable tastes and odors; some certified to remove more than 20 contaminants; KDF technology can help extend carbon filter’s life
Cons: Becomes less effective over time; requires
frequent changing
Cost: $

Water Softener/Exchange System
Pros: Soft water requires less detergent
Cons: Bad for those on diets restricting potassium and/or sodium; banned in some areas because they add salinity to wastewater
Cost: $$

Ultraviolet (UV)
Pros: Extremely effective at removing microorganisms, including bacteria,
viruses and protozoa; point-of-entry treats all water in home
Cons: Continuously consumes electricity
Cost: $$$$

Reverse Osmosis (RO)
Pros: Most recommended for those with compromised immune systems; removes Cryptosporidium parvum, the most troublesome of common parasites
Cons: Slow filtration; consumes several times more water than it filters
Cost: $$$

Pros: Best for very poor water quality
Cons: Significant energy use; water lost through vaporization
Cost: $$-$$$$

Ozone or Ozonation
Pros: Effective in controlling microorganisms; oxidizes contaminants such as iron and manganese
Cons: Can create unwanted byproducts, such as formaldehyde and
bromates; requires additional filtration system
Cost: $$-$$$$

Pros: Effectively eliminates microorganisms; requires no system purchase
Cons: Time- and energy-intensive; water lost through vaporization
Cost: $

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