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Filtered Water vs. Tap Water
Is filtered water safer
than tap water?
BY JULIA
LAYTON
Once
upon a time, "drinking water" meant "tap water" -- the
stuff that comes from a well or, more commonly, a municipal source. It flows
equally into homes, offices, hospitals and restaurants without regard for
social standing or economic status.
Drinking
water was free, it was quick, it had no packaging and no manufacturer's
instructions. Satisfying one's thirst was as easy as holding a glass under the
kitchen tap. Those days are gone.
Drinking
water can be tap, bottled, filtered, mineral, purified, sparkling or enriched.
Municipal, well, domestic, imported or mountain spring. Free of charge or
costlier than gasoline.
The
free stuff is the tap water, the (hopefully) clear liquid that, if you live in
a developed country, flows magically into your home and out of your taps.
At
one time, people didn't give much thought to the source of that magic flow.
They drank it, cooked with it and showered in it. It was presumed safe.
That
presumption has gone the way of the residential landline: It's still out there,
but not in the numbers it once was.
Deserved
or not -- and we'll get to that later -- tap water raises all sorts of alarm
bells these days.
In
the United States alone, people consumed more than 33 billion liters of bottled water in 2007, and more than 40
percent of U.S. homes have some sort of water-treatment system [sources: Discovery, EPA].
So
even when they do hold a glass under the kitchen faucet, they're not drinking
plain old tap water. They're drinking the filtered version, which can cost
anywhere from $20 to a few hundred bucks to produce.
Is
it worth it?
In
this article, we'll find out. We'll look at safety concerns surrounding tap
water and see if they're valid, learn how filtered water is different, and
check out some of the potential downsides of home water treatment.
If
you're not one of the water-treating 40 percent, you may be wondering -- what's
the big problem with tap water?
Safety Concerns
with Tap Water
Tap water's bad press is mostly about three
issues: the way it looks, the way it tastes and what's in it.
The
first two are matters of preference; the third is about safety. Many people who
filter their tap water are concerned about contamination.
Is
it warranted? Not usually, unless the drinker has a severely compromised immune system.
In
the United States, municipal tap water systems have to meet safety standards,
and they're regularly inspected by the government.
The
water is heavily treated to remove particles, chemicals, bacteria and other
contaminants. Typically, chlorine and fluoride are added for disinfection and
dental-health benefits, respectively.
Of
course, no system is perfect, and on rare occasions contaminants such as
pesticides (like atrazine), pathogens (like E. coli, cryptosporidium and
giardia), and fuel byproducts (like MTBE and perchlorate) have been found in
municipal water supplies.
Well
water is more likely than city water to be contaminated, because it doesn't go
through the same regulated treatment and testing.
And
any tap-water supply runs the risk of tasting, smelling or looking bad, simply
because of added chlorine or region-specific, innocuous particles that are not
specifically targeted in the treatment process.
In
the rare case of contamination, the less-rare case of baseless fear of
contamination, or the somewhat common case of aesthetic shortcomings, there are
two typical solutions: bottled water or filtered water.
Bottled
water is a controversial option. It has come out in the last decade that some
bottled water brands are selling $2 liters that are no more pure or
"mountain spring" - like than tap water.
And
for most people with the slightest green-leanings, bottled water's eternal landfill presence and
high-carbon-footprint container makes it a guilty pleasure, at best; at worst,
a vicious, absurdly overpriced and possibly fraudulent assault on the planet.
Which
leaves filtered water. With some smart implementation, it can be a pretty
reasonable approach to cleaning up the tap.
What's the
Difference Between Filtered Water and Tap Water?
If
tap water tastes like chlorine, filtering can fix that. Filtering can clear out
many safety concerns like bacteria, heavy metals and pesticides.
Some
types of filters can do nearly everything. Others are specific to certain
contaminants.
The
most common types of filters in home treatment systems include:
· Activated carbon -- The most common type of filter and a
relatively inexpensive option (it's used in most of those countertop pitchers),
activated carbon attracts and absorbs particles.
Water runs
through a filtering screen containing carbon, where contaminants get stuck. It
can remove much of the heavy metals, parasites, pesticides, radon and MTBE that may be in the water.
This filtering is typically used in point-of-use
devices, like under-sink or faucet-mounted units and pitchers.
· Aeration -- Typically used at the point of entry,
aeration filtering forces water entering the home to pass of high-pressure air
jets.
If there are fuel
byproducts or radon -- contaminants that easily become gases -- in the water,
they evaporate.
Aeration doesn't remove other contaminants like
parasites or mercury.
· Cation exchange -- This is a water-softening filtering approach
that uses positively charged particles to attract negatively charged particles
(ions), such as calcium, magnesium and barium.
Water flows through
beads of resin, where the positive ions stuck to the beads trade places with
the negative ions in the water.
Calcium and magnesium aren't really safety concerns,
but they can damage a home's pipes. However, barium can be a health concern.
· Distillation -- Boiling water is one of the best ways to
remove pathogens and heavy metals, and distillation takes this route.
Distillers boil
water into steam and then condense it back into water, killing bacteria and viruses and pulling contaminants like
lead, mercury and arsenic out of solution in the process.
It's often used in point-of-entry systems (where the
water enters the home) or in countertop devices.
· Reverse osmosis -- One of the most effective and costly
filtering methods and typically a point-of-use approach, reverse osmosis uses
pressure to force water through a semi-permeable membrane, removing practically
all contaminants.
This type of
filtering is recommended for people with compromised immune systems, since it
tends to eliminate more pathogens than other methods.
The downside is the waste: About 4 gallons (15 liters)
get thrown out for every 1 gallon (3.7 liters) of purified water it produces.
· UV Disinfection -- UV disinfection destroys parasites, bacteria
and viruses with ultraviolet light. It doesn't remove other contaminants like
metals or chemicals from water.
UV is often found in
point-of-use, under-sink systems.
All
of these methods can be effective at purifying water, but that's not the end of
the story. Water-filtering systems come with their own set of problems.
Safety Concerns
with Filtered Water
Setting
up a filtering system at home isn't an automatic tap-water fix. It's a potentially good idea
that requires certain steps to implement properly. Without those steps, the
system can be ineffective or, worse, detrimental.
The
first consideration is your specific tap water. Not all water supplies are
alike -- far from it.
To
implement a useful home filtering system, you need to know what you're trying
to filter out. A point-of-entry aerator won't be of any use if you're aiming to
eliminate bacteria.
It's
easy enough to find out what's in your water if you use the city utility
system, which provides water-testing results to its customers every year in the
required Consumer Confidence Report.
If
you haven't received one, you can call your water company and request it.
If
you get your water from a private well or you want to be sure the water coming
out of your faucet is OK (if you've got an old house with lead pipes,
for instance), you can do your own testing.
The
U.S. Environmental Protection Agency or EPA's Safe Drinking
Water Hotline can recommend companies in your area.
There
are two more issues to be aware of when it comes to filtered water.
First,
look for an NSF-certified filter so you know it's doing what it claims. The
National Sanitation Foundation, or NSF, tests water-safety products and
determines whether they meet national and international standards and live up
to their claims.
Finally,
and this is a big one, make sure you maintain the filter the way the
manufacturer recommends, especially in terms of periodic replacement.
If
a filter gets overly clogged with contaminants and you just keep running water
through it, those contaminants can leak into the water, leaving you with more
dangerous water than you started with.
As
with any precautionary action, it's best to start from a position of knowledge.
Especially before investing in a whole-house system, find out what's in your
water, what you want to remove, and how best to do it for your particular
situation.
Smartly
implemented, a filtering system can be an effective and cost-efficient
water-safety measure.
|
Municipal water is heavily treated to remove
particles, chemicals, bacteria and other contaminants.
|
|
Not all water supplies are alike; to filter
effectively, you need to know what contaminants come out of your faucet.
|
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Tap water's bad press is mostly about three issues:
the way it looks, the way it tastes and what's in it.
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