When it comes to water in bottles, there are two kinds of plastic to consider: PET & Polycarbonate. We’ll handle PET first.
PET plastic has the recycle code# 1 under the bottle. Most bottled water comes in PET. There are a couple health concerns of note with PET (ranked from most serious to least):
• Bacteria - It happens when water is left stagnant. Especially when the water is dechlorinated like most bottled waters (plus the bottles are difficult to wash). Most of the health problems associated with this kind of bacteria is diarrhea, stomach upset. This is the chief reason it is not recommended to reuse the bottles.
• Antimony - A few studies have shown antimony trioxide does leach into water from PET plastic over time. The levels are below the EPA standards of antimony. Still a longer range concern.
That’s about it. Bisphenol-A is NOT present in PET. In 2003, DEHP was shown to leech into water after long term storage, but the results have not be accurately reproduced since.
At this point, PET is considered safe by many entities.
On Friday, a group of us set out for the Speakeasy brewery in Hunters Point. We were treated to the BEST brewery tour I’ve ever been on. Kevin, the head brewer, lead us on a hour long tour through the small warehouse. We talked malts, sweet worts, hops, and oh yes…more hops. Kevin was adept at explaining the science behind a good brew….how bitterness develops from enzymatic breakdown of certain proteins, the essential oils that emerge from hops at just right temperature. All the while, we sidled right up to the brewing equipment (we were right on top of the beer!).
It was an amazing tour…they have tours every Friday at 4 PM. More info at Speakeasy’s website.
Welcome to part 4 of 6 on our water choices. (Check out Part 1, 2, and 3).
It’s time to talk taste, cuz the only thing worse than skunked water is skunked beer.
Most people cannot taste the difference in bottled waters or even high quality tap waters. I’ve conducted a number of water taste tests through the years. While individuals may have some preferences, over a large group there tends to be nothing that stands out.
The first questions…should water have a taste? I believe in this crazy thing called evolution…as humans we grew up on water that either bubbled to the surface or from a river/stream. All of those sources would naturally contain minerals from local sources (Ca, Mg, etc.). Those minerals impart taste, so yes water should taste like something.
But let’s focus on the negative, what exactly makes water taste “bad”?
Here is a rough list and some potential causes for that “bad” taste: Note: In SF, we use chloramine instead of chlorine. I’ll go over that issue in my next post.
Chlorine smell - smell w/o taste is an odd situation. It generally means not enough chlorine is in the water. What you are smelling is the unreacted chlorine.
Chlorine smell and taste - this is the more typical too much chlorine in the water. Most humans can taste chlorine to about 5 ppm (some people are sensitive to 2 ppm). The EPA limit is 4 ppm. Most treatment plants shoot for a 3-4 ppm exit concentration at your tap. Certain conditions such as living close to a treatment plant or a system flush may spike the chlorine levels.
Strong Dirt/Earth/Fish smell - Welcome to bacteria/algae country. In warmer areas, this happens seasonally when algae blooms. This is not something you should fix at home, call the water company.
Metallic smell and taste - Most often this is corroding pipes (low ph water can be the culprit). The other potential is natural iron and manganese in the area.
Almost all of these only apply to tap water…I say that because bottled water is almost never treated with chlorine. If it is, some filtration is applied. In either case, these tend to be unlikely. If any of these conditions happened regularly with bottled water, consider it brand suicide.
We’re up to Part 3 of our 6 part conversation on water choices (Check out Part 1 and 2).
We’ve reached your pocketbook…how much does it cost to choose water?
In SF, tap water costs about $3 per 1000 gallons. That translates to $0.0008 per liter. Compare that to most bottled water prices (Aquafina is about $1.50/L, other premium waters run upwards of $2/L).
That’s a 2000 X as much for bottled water. 2000! I can’t think of anything I pay that kind of premium on in my life.
The first fact: 30% of domestic PET production goes towards bottled water currently.
PET plastic is “down cycled”, never remade into plastic bottles because of concerns over bacteria. The PET pellets are then reused for a number of new items: plastic decking to rubber soles on shoes. Check out the quick video to see the process (how plastic would be recycled in the Matrix).
States that have some sort of recycling buyback or tax (CRV) tend to have recycling rates 10-15% higher…kinda an interesting twist. But note the difference in recycling rates of aluminum to PET…25% greater for aluminum. This is the crux of the problem with PET plastic…it is recycled at low rates comparatively to other materials. While the rates continue to rise year to year, we’re still at a low point currently.
Monday, November 17th, 2008 7-9 PMWhere:Atlas Cafe What: Physics for Future Presidents: The Nuclear Reaction Who: Richard Muller, UC Berkeley and LBL The Deets:As we head into a new presidency, much of the debate has been centered on one word: Nuclear. Nuclear terrorism, nuclear power, nuclear proliferation, the mispronunciation of the word nuclear...all have been fervently discussed. But When it comes to the nuclear discussion, isn't the science a key component?
We'll discuss the difference between a Uranium bomb, a Plutonium bomb, and a Hydrogen bomb, the real dangers of nuclear waste, and the danger of radiation. Consider it a crash course on nuclear physics that the next president would appreciate.
Here are some nuggets to chew on:
• Of those killed in the Hiroshima and Nagasaki nuclear attacks, less than 2% died of cancer induced by the radiation.
• 1 square mile of sunlight with current solar cells would provide as much peak power as a nuclear power plant.
• Plutonium is a thousand times less poisonous than botulism toxin, the active ingredient in botox.
• Purified uranium is hard to get, but easy to design into a bomb. Plutonium is relatively easy to get, but hard to make into a bomb. So different kinds of nuclear bombs are difficult to make, but for different reasons. Terrorists are unlikely to be able to make one; the bigger danger is that they could buy one.
Richard A. Muller is professor of physics at the University of California, Berkeley (and my former physics teacher!). He is a past winner of the MacArthur Fellowship. He is the author of Physics for Future Presidents, based on his renowned course for non-science students.
Science in Action Events Science in Action is a series of tours, trips, and hikes intended to put you in the middle of active science in the Bay Area.
If you're interested in attending, send me an email.
November 1st & 2nd What:
Wonderfest - The Bay Area Festival of Science Cost: FREE Details:
WonderFest is the the Bay Area festival of Science. On November 1st & 2nd, there will be free science discussions, art, comedy, and trivia events at both UC Berkeley and Stanfurd. The lineup is jam packed with some of the best talent both university have to offer. You can’t beat the price or the quality.
Here are my picks:
• Saturday 11/1 8:00 pm Does Civilization Have a Promising Energy Future?
• Sunday 11/2 1:30 pm Science Laughs (science comedy)
• Sunday 11/2 2:30 pm Are Dreams Psychologically Significant?
• Sunday 11/2 4:00 pm What Science Must Our Leaders Understand?
