Water Health Series:  Filtration Facts

From EPA Booklet of Same Name
All text original.
See complete original here.

Editors note:  I found this information interesting (albeit a bit dry in a governmental-agency-informational-brochure-kind-of-way).  Visit our Market Place for information on the line of water filters we use and recommend.  Please note that this document is for educational purposes only and is not intended by the EPA to endorse any particular product. 

Home Water Treatment Facts
Americans spend billions of dollars each year on home water treatment units.  According to the Water Quality Association, more than four out of 10 Americans use a home water treatment unit.  These units range from simple pitchers costing less than $20 to sophisticated reverse osmosis units costing hundreds of dollars.  Some people use a home water treatment unit to improve the taste of their tap water. Others treat their water because of health concerns.  While EPA does not endorse specific units, the Agency does set and enforce national standards for the tap water provided by public water systems.  Drinking water can reasonably be expected to contain at least small amounts of some contaminants.  As long as those contaminants are at levels no higher than EPA standards, the water is considered safe to drink for healthy people. People with severely weakened immune systems or other specific health conditions, or those concerned about specific contaminants present in local drinking water, may wish to further treat their water at home or purchase high quality bottled water.  Before purchasing a home water treatment unit, consider local water quality, cost and maintenance of the unit, product performance, and certifications to make sure that the unit will meet your needs.

Local water quality
Begin by learning as much as possible about your tap water. If you haven’t already received it, contact your local water supplier and ask for the annual water quality report (sometimes called a consumer confidence report).This report lists the levels of contaminants that have been detected in the water and shows how these levels compare with EPA’s drinking water standards.  Some contaminant levels remain constant throughout the year, while others vary according to season, weather, or from house to house. For example, lead typically occurs when it leaches from the lead pipes and solder that are in some homes. If you are concerned about a contaminant whose level may vary, consider getting your water tested (use a certified laboratory for the most reliable results). Use this information to help decide on a home water treatment unit.  If your water comes from a household well, EPA recommends annual water testing for nitrates and coliform bacteria.  In addition, check with your health department or local water systems that use ground water for information on contaminants of concern in your area.  Armed with this specific information, you can determine your purpose in buying a home water treatment unit: to remove specific contaminants; to take extra precautions because a household member has a compromised immune system; to improve the taste of the water, or some combination of these concerns.

Cost and Maintenance
Prices vary depending on type (pitcher, faucet filter, etc.), where and how the unit is installed, and what contaminants it removes. Prices can range from $20 for a simple pitcher to hundreds of dollars for a reverse osmosis unit.  All units require some maintenance, and it is important to follow the manufacturer’s recommendations for replacements. For example, activated carbon filters are designed to filter a certain amount of water; after that, the filters become clogged and ineffective. Check the schedule and cost for replacement filters.

The following information briefly describes how different types of home water treatment units work.  For details, read information that accompanies the product and look for independent certification of manufacturers’ claims.  Different units remove different contaminants or classes of contaminants from the water. Sophisticated units may use multiple technologies to remove several types of contaminants and to provide backup protection in case one treatment fails.  A water treatment device can either be free-standing, attached to a tap, plumbed in with a dedicated faucet (also called a point-of-use device) connected to a refrigerator’s water and ice dispensing system; or centrally attached to treat all water entering a house (a point-of-entry device).  For most contaminants, a point-of-use device is effective for treating only the water that is consumed.  However, some contaminants, such as radon, disinfection byproducts, and some organic chemicals, easily turn into gases and may pose a risk when inhaled, such as when showering. A point-of-entry device can reduce concentrations of these contaminants and others that cause aesthetic problems such as scaling, staining, or odor.

Point-of-Use Devices:
Filter pitchers:  Water filtration pitchers are an affordable and commonly used free-standing home water treatment device. Most water pitchers use granular activated carbon and resins to bond with and trap contaminants.  These filters are effective at improving the taste of water, and many will also reduce lead and other contaminants.  Specific contaminants removed vary by model and depend on the pore size and other factors. An activated carbon filter, by itself, is not designed to remove all disease-causing organisms. Carbon filters have a specified shelf life and should be replaced regularly according to the manufacturer’s instructions.
Filters that attach to a faucet or are installed under the sink for a drinking water third faucet: These filters generally use the same technologies as their pour-through pitcher counterparts.  Some filters use fabrics, fiber, or ceramic screening to physically remove contaminants. The most common types use a molded block of activated carbon.  These filters are effective at improving the taste of tap water, and some will also reduce lead, protozoan cysts, and many other contaminants.  Like filter pitchers, shelf lives and specific contaminants removed vary so read the label and instructions carefully.
Distillers:  Distillers heat water to the boiling point, and then collect the water vapor as it condenses, killing disease-causing microbes and leaving most chemical contaminants behind. Contaminants that easily turn into gases, such as gasoline components or radon, may remain in the water unless the system is specifically designed to remove them. Distilled water may taste flat to some people because the water’s natural minerals and dissolved oxygen often have been removed.
Reverse Osmosis Units:  Reverse osmosis units force water through a semi-permeable membrane under pressure, leaving contaminants behind. Reverse osmosis units use approximately three times as much water as they treat, but they are effective in eliminating all disease causing organisms and most chemical contaminants.

Point-of-Entry Devices:
Adsorptive media: Liquids, solids, dissolved or suspended matter adhere to the surface of, or in the pores of, a solid material. Carbon filters use this technology.
Aerators: Aerators force water to travel over air jets. Contaminants that easily turn into gases, such as gasoline components and radon, are removed.  Other contaminants are not.  The water may be additionally filtered after it passes through this system to remove additional contaminants
Water Softeners: Water softeners use a cation exchange resin, regenerated with sodium chloride or potassium chloride, to reduce the amount of hardness (calcium, magnesium) in the water.  The hardness ions in the water are replaced with sodium or potassium ions.  Ion exchange water softeners simultaneously remove radium and barium while removing water hardness.

Make sure that the unit you intend to purchase can address your concerns.  There are three different certifications to look for on the label.  These organizations can also assist you in selecting a device that meets your needs. If a home water treatment unit isn’t certified by one of these organizations, contact the manufacturer directly and ask for proof of the manufacturer’s claims.  Three organizations are accredited by the American National standards Institute (ANSI), and they each certify units using ANSI/NSF standards.  Each ANSI/NSF standard requires verification of contaminant reduction performance claims, an evaluation of the unit, including its materials and structural integrity, and a review of the product labels and sales literature.  Each certifies that home water treatment units perform to meet or exceed ANSI/NSF and EPA drinking water standards. ANSI/NSF standards are issued in two different sets, one for health concerns (such as removal of specific contaminants) and one for aesthetic concerns (such as improving taste or appearance of water).Certification from these organizations will be tied to one or both of these specific standards. NSF International: The NSF Water treatment Device Certification Program requires extensive product testing and unannounced audits of production facilities.  The goal of this program is to provide assurance to consumers that the water treatment devices they are purchasing meet the design, material, and performance requirements of national standards.

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