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  #1  
Old 25 July 2007, 12:31 PM
cobra4j
 
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Default Plastic used for bottled water

I saw we had one bottled water topic- Here's another-

I was told recently it takes gallons of water to make the plastic for one small bottle of bottled water. I don't buy it -

any comments?
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  #2  
Old 25 July 2007, 04:55 PM
Robigus
 
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Spit Take

Well, according to a large number of water fact websites it takes 24 gallons of water to make one pound of plastic. If we assume that the bottle weighs 4 ounces, then it took 6 gallons of water to make the bottle that holds 1 gallon of water.
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  #3  
Old 25 July 2007, 05:10 PM
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Originally Posted by Robigus View Post
Well, according to a large number of water fact websites it takes 24 gallons of water to make one pound of plastic. If we assume that the bottle weighs 4 ounces, then it took 6 gallons of water to make the bottle that holds 1 gallon of water.
Does a plastic bottle even weight one ounce, let alone 4 ounces?
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  #4  
Old 25 July 2007, 07:25 PM
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I was making an assumption (yes, I know) about the weight of a 1 gallon bottled water container. According to this website, a typical half-liter water bottle weighs 13-16 grams (less cap). Figuring 1/2 ounce per bottle, that would make it 3/4 of a gallon of water to make each 1/2 liter water bottle. Still seems a little uneven.
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  #5  
Old 26 July 2007, 12:40 AM
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What exactly is meant by "it takes"? Water could just be used as the coolant to cool the machines and the plastic being molded.
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  #6  
Old 26 July 2007, 02:06 AM
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Originally Posted by ASL View Post
What exactly is meant by "it takes"? Water could just be used as the coolant to cool the machines and the plastic being molded.
In which case it would be reused, yes?
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  #7  
Old 26 July 2007, 02:29 AM
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Maybe they do pump the heated coolant water to a tank to cool and re-use it. More likely the used coolant water is discharged into the sewers and fresh water drawn from the mains. It doesn't 'use water' but it does use the resources needed to filter it, purify it to a standard acceptable for the machines, and pump it.
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  #8  
Old 26 July 2007, 03:28 AM
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In any event, it's not like they're taking 10 pounds of water, doing some voo-doo to it, and chemically altering it to make half an ounce of plastic with the rest of the mass just disappearing... I almost get the feeling that that's how some people are looking at the problem.
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  #9  
Old 26 July 2007, 05:24 AM
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Perhaps they got confused when they heard about bottled reverse-osmosis water? RO requires large amounts of water to purify a smaller amount; basically by forcing all the contaminants from the smaller amount into the larger amount. Thus, 1 gallon of RO water may require disposal of 4 gallons of water (or, at least that's how under-sink units work - large facilities may be able to filter and reuse that water somehow).

Henry
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  #10  
Old 26 July 2007, 06:13 AM
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Quote:
Originally Posted by ASL View Post
What exactly is meant by "it takes"? Water could just be used as the coolant to cool the machines and the plastic being molded.
I don't think so. I think the production of the plastics themselves requires water at at least one stage. While I agree that it's not as if some voodoo is performed on water and voila - plastic, it is also not simply a matter of performing some voodoo on the oil, cool the machines with water, and voila - plastic. Most synthetic chemicals require and/or produce water at one or more points in the process. (Someone who's better with organic chemistry can help me with this part?) Also, water is required to clean the machines and to clean the products before they are used and most of this water cannot be reused. So I don't think it's very wrong to say "it takes".
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  #11  
Old 01 September 2007, 03:04 PM
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Originally Posted by ganzfeld View Post
I don't think so. I think the production of the plastics themselves requires water at at least one stage.
That may be true, but there's no way 10 gallons of water could actually be used up to make 4 oz of plastic. The conservation of mass (and energy) will not let 80 pounds (40kg) disappear.
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  #12  
Old 02 September 2007, 07:14 PM
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Originally Posted by trlkly View Post
That may be true, but there's no way 10 gallons of water could actually be used up to make 4 oz of plastic. The conservation of mass (and energy) will not let 80 pounds (40kg) disappear.
I think the issue isn't that the water is consumed into the plastic, but is made use of then discarded: some of it to cool hot machinery, some of it to dilute chemicals, some of it to wash out the finished product, etc. Much of the water would be re-usable, but some of it would be polluted by the process and require treatment before it could safely be discharged.

Silas
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  #13  
Old 02 September 2007, 07:30 PM
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Is the suggestion that it takes more water to make plastic bottles for water than for other drinks?
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  #14  
Old 02 September 2007, 07:37 PM
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Originally Posted by Chloe View Post
Is the suggestion that it takes more water to make plastic bottles for water than for other drinks?
I don't think so. Whatever water is used in the industrial process would be the same if the bottle was to be used to hold water, cola, methylated spirits or drain cleaner.

I think the idea is that if it takes substantially more water to make a bottle than the volume of it's contents, and the bottle is intended to hold water, then just get the water you drink from a tap or a spring.
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  #15  
Old 02 September 2007, 09:45 PM
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Originally Posted by Eddylizard View Post
. . . I think the idea is that if it takes substantially more water to make a bottle than the volume of it's contents, and the bottle is intended to hold water, then just get the water you drink from a tap or a spring.
Which suggests the next question: how much water is required for the manufacture of the pipelines, in-house piping, tap, sink, valves, etc. for providing tap water to a home?

Here in Southern California, all the water has to come over hundreds of miles of canals and pipelines, all of which require water in their manufacture: how much water had to be expended, say in the mixing of concrete, to bring each gallon of tap water to us in our desert cities?

Anyway, if people feel acutely about this, they can help by buying water in five-gallon containers rather than in one-pint containers. The ratio of container to payload decreases as the size increases.

Silas
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  #16  
Old 04 September 2007, 04:55 PM
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Here is a video explaining the process from start to finish. Apparently Ball does use water to cool the molds, but that cooling water would be recycled and reused.
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  #17  
Old 04 September 2007, 04:57 PM
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Quote:
Originally Posted by Eddylizard View Post
I think the idea is that if it takes substantially more water to make a bottle than the volume of it's contents, and the bottle is intended to hold water, then just get the water you drink from a tap or a spring.

And don't drink soda at all?
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  #18  
Old 04 September 2007, 05:00 PM
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Quote:
Originally Posted by Chloe View Post
And don't drink soda at all?
I was merely saying that was the premise in the OP, not whether it was correct, incorrect or that one should or shouldn't purchase water, other beverages or other products in plastic bottles.
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  #19  
Old 04 September 2007, 05:04 PM
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Quote:
Originally Posted by Eddylizard View Post
I was merely saying that was the premise in the OP, not whether it was correct, incorrect or that one should or shouldn't purchase water, other beverages or other products in plastic bottles.
I didn't mean to pick on you, but while it makes sense that that's the premise, in reality this sort of thing is used only to attack bottled water drinkers. We've had threads here saying how stupid bottled water drinkers were to spend so much on a bottle of water, with no recognition of the fact that soda drinkers are spending the same amount and drinking something much less healthy. And the OP specifically refers to water bottles, so I read it as more of the same.
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  #20  
Old 04 September 2007, 05:06 PM
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Quote:
Originally Posted by Chloe View Post
Is the suggestion that it takes more water to make plastic bottles for water than for other drinks?
[tangential tidbit]
More PET is used in soda bottles than in similar volume water bottles. Soda bottles need to be thicker due to the carbonation. Or so I read in an artlicle last week in the Wall Street Journal about some bottlers making their water bottles with less plastic than they currently contain.
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