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Tap water

  1. Sep 4, 2004 #1
    Is it safe to drink tap water?
     
  2. jcsd
  3. Sep 4, 2004 #2

    ShawnD

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    For the most part, tap water is safe. It's only dangerous if your water pipes are made of lead, or there is a known virus/bacteria in the water.
     
  4. Sep 4, 2004 #3

    Moonbear

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    It might depend on the source of your tap water. If it's municipally supplied, it should be fine (occassionally, such as after major flooding, the supply will be contaminated and munipalities will issue warnings to boil the water before use or to temporarily use bottled water). If you have well water, then you need to have your well tested regularly to determine it is safe. What ShawnD said about lead pipes is also relevant. Of course, I can only speak for those living in the US and Canada. I believe most developed countries have similar standards, but I don't know for certain.
     
  5. Sep 4, 2004 #4

    Monique

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    depends which country you're in..
     
  6. Sep 4, 2004 #5
    Science magazine - Hidden Cost to Treated Water?

    • Science magazine, 2 September 2004

      Hidden Cost to Treated Water?



      Disinfecting drinking water with chloramines, a chlorine-ammonia mix that is used to treat roughly a third of the drinking water in the United States, may have the unintended consequence of producing toxins, a new study suggests.

      Although chlorine remains the most widely used disinfectant in the United States, the popularity of chloramine has been growing, in part due to the perception that it is safer because it has fewer byproducts. Chlorine creates potentially harmful byproducts when it reacts with other compounds normally present in drinking water systems. Most scientists blame disinfection byproducts for a link between water disinfection and risk of bladder cancer or miscarriages in humans, but they don't know which of an estimated 2000 byproducts are the culprits....

      When a 2002 EPA drinking water survey found another potentially hazardous type of compound -- so-called iodinated byproducts -- in drinking water from a Texas utility using exclusively chloramine, the discovery came "as a complete surprise," says Susan Richardson, an EPA chemist who headed the survey. Now she, toxicologist Michael Plewa of the University of Illinois, Urbana-Champaign, and colleagues have identified five of the iodinated byproducts. One of these, iodoacetic acid (IA), is the most toxic to mammalian cells of any disinfection byproduct ever tested, they reported online on 17 August in Environmental Science & Technology.


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    Edit: This is an excerpt of an article that was published in ScienceNow, not Science. ScienceNow is apparently a sub-publication of Science that covers daily science news. I left out caviats that were present in the original article and only included the most alarming statements. Further research is needed in order to reliably determine the extent of the hazard posed by disinfection products and byproducts present in public water supplies. The Richardson/Plewa article in Environmental Science & Technology has not yet been print published but has appeared online and can be linked to directly here (full-text HTML and PDF links are at the bottom of the page).
     
    Last edited: Sep 5, 2004
  7. Sep 4, 2004 #6

    Moonbear

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    Hitssquad, wow! I had no idea about this. I have to wonder who thought up the idea of a chlorine-ammonia combination for drinking water though...don't environmental engineers have to pass chem 101 that teaches that's a toxic combination?

    Are the by-products a danger in the drinking water, or to the environment around the water treatment plant? I guess I'll have to read the article.

    ----

    I just read the article linked. About the only thing left out of the quote was the comment that the amounts of the iodinated by-products are probably too low to pose any risk at all. Guess we have to wait to see how that turns out. I'm sure now that it's being publicized, someone will be testing concentrations in drinking water supplies. Also, for those who are interested, the article is in ScienceNow, not Science. The link is correct though.

    ---
    Just one more edit:
    Hitssquad, did you find the article referenced in Environmental Science & Technology? I went to their site, and there is no Aug 17 issue. There is an Aug 15 issue, but I don't see anything in it by Susan Richardson. There is an article by Plewa, but it's about a pesticide, not drinking water disinfectants. Granted, pesticides are bad things to have getting into the water supply too, but that's different than the water treatment itself causing problems. Did I miss something?
     
    Last edited: Sep 4, 2004
  8. Sep 4, 2004 #7

    Moonbear

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    In case anyone is wondering, here is the abstract of the article referenced in the ScienceNow report. There seems to be a disconnect between what the authors of the ScienceNow report are asserting and what the cited reference actually addresses.

     
  9. Sep 5, 2004 #8
    More like area of country. The US is a good example of bad water and good water depending on where you live. As I hear, the Pacific Northwest has great water while Houston Texas water is not so great.

    I usually drink spring water, which is obviously, gathered from the PNW in North America.

    Anyways, maybe you guys may want to take a look at this. It's extremely surprising to find what's in US tap water.
     
  10. Sep 5, 2004 #9
    Correct abtract for disinfection-byproduct toxicity article

    That is the wrong article. The authors of the article referenced in the ScienceNow report are Plewa, Wagner, Richardson, Thruston, Woo and McKague. Here is the abstract (full-text links are at the bottom):


    • Chemical and Biological Characterization of Newly Discovered Iodoacid Drinking Water Disinfection Byproducts

      Iodoacid drinking water disinfection byproducts (DBPs) were recently uncovered in drinking water samples from source water with a high bromide/iodide concentration that was disinfected with chloramines. The purpose of this paper is to report the analytical chemical identification of iodoacetic acid (IA) and other iodoacids in drinking water samples, to address the cytotoxicity and genotoxicity of IA in Salmonella typhimurium and mammalian cells, and to report a structure-function analysis of IA with its chlorinated and brominated monohalogenated analogues. The iodoacid DBPs were identified as iodoacetic acid, bromoiodoacetic acid, (Z)- and (E)-3-bromo-3-iodopropenoic acid, and (E)-2-iodo-3-methylbutenedioic acid. IA represents a new class (iodoacid DBPs) of highly toxic drinking water contaminants. The cytotoxicity of IA in S. typhimurium was 2.9× and 53.5× higher than bromoacetic acid (BA) and chloroacetic acid (CA), respectively. A similar trend was found with cytotoxicity in Chinese hamster ovary (CHO) cells; IA was 3.2× and 287.5× more potent than BA and CA, respectively. This rank order was also expressed in its genotoxicity with IA being 2.6× and 523.3× more mutagenic in S. typhimurium strain TA100 than BA and CA, respectively. IA was 2.0× more genotoxic than BA and 47.2× more genotoxic than CA in CHO cells. The rank order of the toxicity of these monohalogenated acetic acids is correlated with the electrophilic reactivity of the DBPs. IA is the most toxic and genotoxic DBP in mammalian cells reported in the literature. These data suggest that chloraminated drinking waters that have high bromide and iodide source waters may contain these iodoacids and most likely other iodo-DBPs. Ultimately, it will be important to know the levels at which these iodoacids occur in drinking water in order to assess the potential for adverse environmental and human health risks.
     
    Last edited: Sep 5, 2004
  11. Sep 5, 2004 #10
    Why the Plewa article does not show up in the published issues of ES&T

    My guess would be that in the small amounts they use, the chlorine-ammonia combination itself genuinely is relatively non-toxic, as the problem turned out to be with the by-products of that disinfection product.



    It has not been published in print yet. To find the article, you have to click on the Research ASAPs tab (in the row of green tabs at the top). There you can see before-print research web-published daily. (This is research that has already gone through the peer-review process {the ones I saw all say "accepted on [so-and-so date]"}, so it is just as legitimate as the research that has already seen print.) Search the text of the page for Plewa, or scroll down to Aug 17.
     
    Last edited: Sep 5, 2004
  12. Sep 5, 2004 #11

    Moonbear

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    Hitssquad, thanks for pointing me to the correct article. I got confused that there was an issue with such a close publication date and one of those authors published in it. :confused: I didn't see that ASAP tab at the top. :redface: Well, the other article was interesting too, even if on a slightly different topic. Now I'll read the right one. :smile:
     
  13. Sep 5, 2004 #12

    Moonbear

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    Okay, this is from the same article mentioned by Hitssquad as cited in the ScienceNow article.

    Since I was confused earlier, I'll repeat the citation of the one I'm referring to now so we all know we're talking about the same thing. :smile:

    Environ. Sci. Technol., ASAP Article 10.1021/es049971v S0013-936X(04)09971-7 Web Release Date: August 17, 2004
    Chemical and Biological Characterization of Newly Discovered Iodoacid Drinking Water Disinfection Byproducts

    Michael J. Plewa* and Elizabeth D. Wagner, Susan D. Richardson and Alfred D. Thruston, Jr., Yin-Tak Woo, A. Bruce McKague

    So, I'm no expert in toxicology, but the methodology seemed sound from my perspective. No qualms there. My initial concern that they only sampled water post-treatment was quickly alleviated when I checked into the 2002 report of an EPA study that they cited which initially identified these compounds in finished water. That study did analyze both sources (raw water) and finished water, so we can be more confident that these were not just contaminants that were not removed during the purification process, but something actually formed as a by-product as that process. I'll note that the source water for the plants with this problem sounded pretty bad to begin with, in my non-expert view.

    But, before everyone panics about their drinking water, here is a quote from the Plewa et al. article from the implications and future directions section.

    So, to reiterate, actual concentrations of IA in the water have not yet been determined, so whether they get anywhere close to the levels that caused toxicity in in vitro studies is not known yet. It also sounds like the outcomes of these studies can be used to tailor treatment processes to better suit the source water. It also sounds like chlorination prior to chloramination reduces or removes these by-products (technically, the chemical precursors that form these by-products).

    There was also a note in the EPA study that while some by-products are stable, many degrade during the distribution process, meaning they don't actually make it to your tap. They don't know yet how stable IAs are (or at least they didn't in the 2002 report, and there is no indication of anything more current about that in the Plewa et al. article).
     
  14. Sep 5, 2004 #13
    So guys, can I drink water from the tap in Toronto or not?You confusing me a lot with your reports and scientific stuff! :wink:
     
  15. Sep 5, 2004 #14

    Moonbear

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    Well, here's an FAQ specifically regarding Toronto water. http://www.city.toronto.on.ca/water/faq.htm

    The studies we're discussing above deal with U.S. water supplies. I think if I lived in Texas, I might want to take my chances on bottled water, otherwise, no guarantee their sources are any better. Bottled water has to be purified too, but I don't know what methods various companies use.

    You might find this news article interesting: http://news.bbc.co.uk/2/hi/uk_news/3523303.stm
     
    Last edited: Sep 5, 2004
  16. Sep 6, 2004 #15

    Phobos

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    I'm less familiar with Canada's drinking water quality than I am with the U.S.'s but I would suspect that the answer is yes. (see Moonbear's link)

    Large cities have strict testing & water quality requirements. From what I have seen, Canada's drinking water technologies are very good.

    As was mentioned, one concern might be if you lived in a house with lead solder in its pipes (because the lead will leach into the water).
     
  17. Sep 6, 2004 #16

    Phobos

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    Environmental engineer here (although it's been a while since I've done drinking water studies).

    Drinking water disinfection is a tricky balance between the risk of pathogens and the risk of disinfection by-products (DBPs). In the US, chlorine is the #1 used disinfectant. It works great against pathogens, but it does create many undesireable DBPs. Treatment plant operators must balance the disinfectant dosage to achieve the regulated pathogen-kill (e.g., 99.9% or 99.99%, depending on the pathogen type) vs. the DBP residual that is created. DBP regulations have been getting stricter lately which inspires/forces facilities to modify their existing operations (like additional filtering) or look for alternative disinfection technologies.
     
  18. Sep 6, 2004 #17

    Phobos

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    Correct - - the larger the municipality, the stricter the requirements on the drinking water quality...not because city-folk are more important, but because a 1 in 100,000 risk (or whatever) is more significant in a city of millions than it is in a small town of a few thousand.

    However, sometimes cities usually have less-clean source waters than small towns so they have to use more disinfection chemicals, which means more DBPs.
     
  19. Sep 6, 2004 #18

    Phobos

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    A good point. The laws are strict toward public-supplies, but I'm not aware of any for bottled water companies (treated like a food product perhaps?). But I know those companies do some degree of testing. My guess would be that any physical/chemical treatment is some type of straightforward filtering and there may be no biological disinfection. I'd have to research it (and I suspect that such companies keep that information close whereas municipalities are required by law to make their test results available to the public).
     
  20. Sep 6, 2004 #19

    Phobos

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    FWIW, chlorinated DBPs are well known/studied/monitored (and are the most common). Brominated DBPs (less common) have become a new concern over the past decade or two & are getting more attention. Iodoacid-type DBPs are something new to consider...don't freak about about them yet.
     
  21. Sep 6, 2004 #20

    Moonbear

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    From what I've found, it seems the FDA regulates bottled water as a packaged food product, unless it's sterile water, in which case it gets regulated as a pharmaceutical (probably because most uses of sterile water would be in hospital settings). A few bottled water companies outline their purification processes. Some start with municipal water and others spring water. It seems most go through a few reverse osmosis filtration steps, one I found had a final ozone treatment step. I think the main thing is they filter out things like the chlorine in tap water to improve taste. Since they bottle it instead of sending it through long distances of pipelines, they don't need to leave any residual chlorine to keep it disinfected on the way to someone's home.
     
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