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Water Filters

What To Look For

Filters only reduce selected contaminants. Therefore, be sure you know which pollutants you're targeting before purchase, and select a filter certified by the National Sanitation Foundation (NSF), as all the above filters are. When a product effectively reduces at least 93 percent of a particular contaminant, NSF certifies the filter for reduction of that contaminant.

Following are basic criteria to use when choosing a water filter:

Type

Carafe: Portable pour-through carafes are the simplest and cheapest filtration option. They use carbon filters, and most models require a filter change about every two months. For basic filtering and taste improvement, Brita pitchers work fine. Pur filters remove a wider variety of contaminants, but they've been found to clog easily. However, in areas with herbicides or other chemical contaminants that Brita filters can't remove, Pur is the least costly option.

Faucet Mount: Faucet mounted filtration systems also use carbon filters but eliminate the wait-time associated with carafes. The filter cartridges should be changed every three months.

Counter Top: Counter-top models are either manual-fill units, or they're filled via a tube connected to your faucet. They generally use either carbon filters or distillation.

Under Counter: Under-counter systems attach to the water pipes under your sink and provide hot or cold filtered water through your existing tap or a separate faucet (filter units requiring a separate faucet usually have high installation costs). The water flow with these systems tends to be better than with faucet-mounted systems, and filters generally only need changing twice a year.

Whole House: Whole house systems filter all household water, whether used for bathing, washing or drinking, before it comes into the home. When sediment in water is a problem, whole house systems can in fact prolong the life of major appliances, but they usually are ineffective at removing lead, chloroform, pesticides, and bacteria.

Portable Filters: Some reusable water bottles come equipped with a filtration system inside the bottle. Most remove chlorine, bad tastes and odors, as well as an assortment of heavy metals including lead, mercury, and copper.

Filtration Method

Carbon: These use activated carbon to adsorb lead, chlorine byproducts, certain parasites, radon, solvents, some pesticides and herbicides, and some organic chemicals as well as odors and bad tastes. They won't remove heavy metals, arsenic, nitrites, bacteria or microbes.

Distiller: Distillers boil water into steam, then condense it back into water in a separate chamber, leaving behind particles and total dissolved solids. Since water is heated, distillers kill microbes. They eliminate many other pollutants including trivalent arsenic, fluoride, lead and mercury , but not volatile organic chemicals and chlorine, which are usually removed by an accompanying carbon filter. Upfront costs for distillers are steep, between $200 and $1500. They also use considerable amounts of energy: It takes one kilowatt-hour to produce one liter of distilled water. Because the average person uses 100 gallons of water per day, a whole-house distiller can increase daily home energy use by 378 kWh. If heavy metals are a problem, consider a counter top distiller for your drinking water only. Distilled water contains less dissolved oxygen, and many find that the water tastes flat.

Reverse Osmosis: Reverse-osmosis systems, typically expensive and difficult to install, operate by pushing water through a membrane, then flushing away a few gallons of contaminant-containing water for every gallon purified. These systems are the only filters that remove nitrates and perchlorate. They also remove industrial chemicals, heavy metals, chlorine byproducts, arsenic and asbestos but not radon or 100 percent of pesticides, which can be removed by an additional carbon filter. (As these filters waste enormous amounts of water and flush contaminants back into the water supply, they should be considered a solution to water contamination only if nitrates and perchlorate are problems in your area). The membrane generally needs to be replaced every two to three years.

Ceramic: Ceramic filters, often combined with carbon filters, will remove bacteria, parasites, asbestos and sediments. As water passes through the pores of the ceramic, particles as small as .2 microns are trapped. When the water flow is reduced, the filter requires a light scrub under running water. Ceramic filters are available in both counter-top and under the counter models, and are often combined with another filtration method.

UV: These use a 60-watt ultraviolet light bulb to kill giardia, E.coli, and Cryptosporidium, and are currently the only systems certified by the NSF to do so. Although the bulb is continuously lit, UV systems are more energy-efficient than distillers and are available in under the counter models and whole house units. UV purifiers are not certified to remove pathogens uncommon to North America such as toxoplasma and entamoeba and should be used in conjunction with another filtration method.

Contaminants Removed

Contaminants vary for each water supply, but those most frequently found include:

2,4-D: a common herbicide and suspected hormone disruptor

Arsenic: a heavy metal that has been linked bladder, lung, kidney, prostate and skin cancer in animal tests, heart and nervous system damage and skin problems; can enter water through natural soil deposits or industrial and agricultural pollution. Very low levels of arsenic have also been found to disrupt hormone functions.

Atrazine: an herbicide used on corn; short-term exposure leads to lung, kidney and heart congestion while long-term exposure may cause cardiovascular disease. Atrazine is a suspected hormone disruptor.

Chloramine: a chlorine-ammonia compound used as a disinfectant in 29 percent of U.S. water utilities; has been associated with asthma, rashes and fainting

Coliform bacteria: Not harmful in themselves, they may indicate the presence of dangerous microbes such as Cryptosporidium, which can be life-threatening to people with weak immune systems.

Cysts: microorganisms including Cryptosporidium and Giardia that are carried by animal and human waste and linked to gastrointestinal illness. Crypto can be life-threatening for those with weakened immune systems.

E.coli: a type of fecal coliform bacteria that can cause gastrointestinal illness; about 2 to 7 percent of E.coli of infections lead to kidney failure.

Lead: a brain-damaging and neurotoxic heavy metal that can enter water via decaying pipes and taps; "Every homeowner, especially if they have children under six, should have their water tested for lead," warns Erik Olson, a senior attorney specializing in drinking water at the Natural Resources Defense Council.

Lindane: used as an insecticide and in prescription medications for head and body lice; a known hormone disruptor

Mercury: a brain-damaging heavy metal that can also cause kidney damage

Misc. heavy metals: Carcinogenic chromium can also cause upset stomach, ulcers, kidney and liver damage and death. Short term exposure to selenium, cadmium and copper can nausea, vomiting and diarrhea, and long term exposure to cadmium and copper can cause kidney disease.

MTBE: The gasoline additive methyl tertiary-butyl ether (MTBE) leaks into groundwater from underground fuel storage, spills and storm-water runoff and is a possible carcinogen. MTBE has been banned in many but not all states.

Nitrates: come from animal waste on cattle farms, on feedlots and in dairies, and can cause "blue-baby syndrome," which prevents blood from holding oxygen.

Perchlorate: contaminant derived from rocket fuel; causes thyroid damage and is a possible carcinogen

Perchloroethylene (PERC)/tetrachloroethylene: PERC, also commonly listed as tetrachloroethylene, is the main solvent used in most dry-cleaning processes. It is a known carcinogen that can cause neurological, kidney and liver effects, and has been associated with reproductive effects such as spontaneous abortion.

Simazine: a common pesticide; long-term exposure may lead to liver and kidney damage

Trihalomethanes (THMs): Chemicals formed when chlorine used to disinfect water reacts with organic matter, such as animal waste, treated sewage or leaves and soil. They can increase the risk of cancer and may damage the liver, kidneys and nervous system, and increase rates of miscarriage and birth defects.

Total Dissolved Solids (TDS): inorganic salts, such as calcium, sodium and sulfates, and small amounts of organic matter that are dissolved in water; the concentration of TDS in water is not a health hazard but can cause water to be corrosive or salty in taste and may lead to mineral build-up.

Toxaphene: a now-banned insecticide that breaks down slowly in the environment and is an EPA-classified probable carcinogen; high level exposure could damage the lungs, nervous system and kidneys.

VOCs: Including benzene, which can cause cancer and birth defects and toluene, which can cause nausea, weakness, confusion and hearing and vision loss.

Annual Filter Cost

The dollar amount refers to the cost of replacing filters for one year.