Statistics:

• 24% of the bottled water on the U.S. market, including Pepsi’s Aquafina and Coke’s Dasani, is filtered tap water.¹
• The San Francisco Department of Public Health has determined that their tap water costs the consumer $.03 per gallon, over 300 times less than the same amount of a typical bottled water²
• A Brita faucet filter can remove 99% of existing lead and chlorine from municipal tap water³

Making the switch
Given the environmental impact of the bottled water industry, I have a clear conclusion in mind: I don’t want it. Two questions remain, however:

1) Is bottled water more “pure” than tap water

2) What’s the best way to filter tap water?

To answer the first question, I’ll ask two others: what microbial demons reside in tap and bottled water, and who regulates it? Tap water regulation falls under the jurisdiction of the Environmental Protection Agency (EPA), while the Food and Drug Administration (FDA) regulates bottled water. Both groups consistently screen for water contaminants ranging from microorganisms (i.e. giardia) to disinfectants (i.e. chlorine) to inorganic chemicals (i.e. lead). ⁴

EPA and FDA standards for safe drinking water are very similar, and if one were to rate which agency had stricter regulations, it would be the EPA with tap water. In fact, a published article from the FDA’s website states: “Each time the EPA establishes a standard for a chemical or microbial contaminant, the FDA either adopts it for bottled water or makes a finding that the standard is not necessary for bottled water in order to protect the public health.”⁴

Should we filter?
Even with these assurances, medical opinions range from declaring tap water (and bottled tap water) as completely safe to potentially hazardous for your health. I personally am not going to turn my nose to every water fountain I pass, but knowing how many environmental factors can influence our water sources, I want to filter my water at home.

To filter water that does come from public water sources, bottled water companies typically use either reverse osmosis, deionization, or activated carbon filtration, all processes that are available to those of us who want to filter our tap water.⁵ I think this spells out a clear answer that filtered water can be just as “pure” as bottled water, it’s a lot less expensive, and drinking it has very little negative environmental impact.

Filtering tap water
Here’s a quick primer on three typical water purification methods:

Carbon filtration is very common (i.e. Brita filters). With this method, water filters through some form of charcoal, which has high surface area, and the charcoal absorbs many unwanted chemical compounds, removing them from the water.

“In reverse osmosis, mechanical pressure is applied to an impure solution to force pure water through a semi-permeable membrane.”⁶

“Distillation involves boiling the water to produce water vapor. The vapor contacts a cool surface where it condenses as a liquid,” thereby removing many contaminants.⁶

Word on the street
Of these three methods, distillation seems to be the most effective in removing contaminants, followed by reverse osmosis, followed by carbon filtration. The principal issue with carbon filters like a Brita filter is that they become less effective more quickly and can render you complacent when in fact you’re drinking unfiltered tap water.⁷ I, for one, probably have mold growing in my Brita carbon filter, it’s been there so long. That’s no good. Another note: most water filter systems will filter out any fluoride in the water, so consider (especially parents) another source of fluoride like a mouthwash for dental health.

To compare price for three filters (one for each method):

Carbon filter: Price ranges from$.09 per gallon (Aquasana) to $.25 per gallon (Brita water pitcher)³

Reverse Osmosis Unit: Unit costs range from $250 to $600. Estimates range widely from$.06 to $.24 per gallon⁸

Distiller: Unit costs range from $250 to $1500. Price estimated between $.14 and $17 per gallon⁹

These are prices and methods that I came across, but now I want to hear from you. If you’ve experimented, which process do you think works best? What opinions do you have about whether filtering tap water is necessary? What sayeth you?

A comment from my friend Aaron on my Water 2 entry:

My refrigerator has a water dispenser, and that is where most of the family’s drinking water comes from. In my continuing effort to limit our intake of lead, I put a water filter in the line to the frig. It was surprisingly easy. I screwed the filter holder to the wall behind the refrigerator, cut the water line (Don’t forget to turn off the water at the street!), and inserted the two cut parts into the filter holder. You need to change the filter (super easy) every six months or so.

1. http://www.fastcompany.com/magazine/117/features-message-in-a-bottle.html [↩]
2. http://www.sfdph.org/phes/water/FactSheets/bottled_water.pdf [↩]
3. http://www.waterfiltercomparisons.net/WaterFilter_Comparison.cfm [↩] [↩]
4. http://www.fda.gov/FDAC/features/2002/402_h2o.html [↩] [↩]
5. http://www.msnbc.msn.com/id/5467759/ [↩]
6. http://en.wikipedia.org/wiki/Water_purification [↩] [↩]
7. http://www.holycross.edu/departments/chemistry/jvandore/AnalytPresentIP2004/Brita_Filter_Project.ppt [↩]
8. http://www.freedrinkingwater.com/products.htm [↩]
9. http://extension.missouri.edu/explore/hesguide/houseeq/gh4863.htm [↩]