Is it Safe to Drink Tap Water? Know the Facts

[tumor]

Is it safe to drink tap water?

 

[ShawnD]

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.

 

[Moonbear]

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.

 

[Monique]

Is it safe to drink tap water?

depends which country you're in..

 

[hitssquad]

Science magazine - Hidden Cost to Treated Water?

Is it safe to drink tap water?

• http://sciencenow.sciencemag.org/cgi/content/full/2004/902/2 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 http://cropsci.uiuc.edu/faculty/plewa/index.cfm .

---
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 http://pubs.acs.org/cgi-bin/asap.cgi/esthag/asap/abs/es049971v.html (full-text HTML and PDF links are at the bottom of the page).

 

[Moonbear]

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?

 

[Moonbear]

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.

Environ. Sci. Technol., 38 (16), 4383 -4389, 2004. Copyright © 2004 American Chemical Society

Alteration of Mammalian-Cell Toxicity of Pesticides by Structural Iron(II) in Ferruginous Smectite

Kara C. Sorensen, Joseph W. Stucki,* Richard E. Warner, and Michael J. Plewa

Abstract:

The ultimate concern over pesticides in the environment is their toxic impact on nontarget organisms, including humans. Soil clays are known to interact with pesticides in ways that decrease the concentration of the parent compound in the soil solution (adsorption, sequestration, degradation). These phenomena are generally regarded as beneficial, but toxicological verification is lacking. In this study, mammalian-cell cytotoxicity of four commonly used agricultural chemicals (2,4-D, alachlor, dicamba, and oxamyl) was assessed after exposure to either reduced or oxidized ferruginous smectite (SWa-1). Results revealed that treatment with reduced smectite produced differential effects on mammalian-cell viability, depending on the pesticide. Oxamyl and alachlor reacted with reduced SWa-1 showed a significant decrease in their overall cytotoxic potential. Dicamba reacted with the reduced-clay treatment and generated products that were more toxic than the parent pesticide. Finally, no differences were observed between redox treatments for 2,4-D. The significance of these results is that oxidized smectites have virtually no influence on the toxicity of pesticides, whereas reduced-Fe smectite plays an important role in altering the cytotoxic potential of agricultural pesticides. The Fe oxidation state of clay minerals should, therefore, be taken into account in pesticide management programs.

 

[Dagenais]

depends which country you're in..

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.

 

[hitssquad]

Correct abtract for disinfection-byproduct toxicity article

In case anyone is wondering, here is the abstract of the article referenced in the ScienceNow report.

Kara C. Sorensen, Joseph W. Stucki,* Richard E. Warner, and Michael J. Plewa

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 http://pubs.acs.org/cgi-bin/asap.cgi/esthag/asap/abs/es049971v.html (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.

 

[hitssquad]

Why the Plewa article does not show up in the published issues of ES&T

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?

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.

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.

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). http://pubs3.acs.org/acs/journals/toc.page?incoden=esthag&indecade=&involume=0&inissue=0 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.

 

[Moonbear]

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. I didn't see that ASAP tab at the top. Well, the other article was interesting too, even if on a slightly different topic. Now I'll read the right one.

 

[Moonbear]

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.

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.

Research is planned to obtain quantitative concentration data for these iodoacids in drinking water. In the nationwide occurrence study, these iodoacids were found only in drinking water from one location that was treated with chloramines (and whose source waters were high in bromide/iodide) (23). Interestingly, the highest levels of iodinated THMs (trihalomethanes) (dichloroiodomethane, bromochloroiodomethane, dibromoiodomethane, chlorodiiodomethane, and bromodiiodomethane) were also observed in this same drinking water at a total of 18.7 g/L (which was 81% of the concentration of the four regulated THMs-chloroform, bromoform, bromodichloromethane, and chlorodibromomethane) (23). These findings are consistent with earlier work by Bichsel and von Gunten that predicted an increased formation of iodinated DBPs in chloraminated drinking water, based on the very slow rate of iodide oxidation to iodate by chloramines, which allows hypoiodous acid (HOI) to ac cumulate and react with natural organic matter to form iodinated DBPs (36, 37). Thus, it is likely that the highest levels of iodoacids (and other iodo-DBPs) will not be in chlorinated drinking waters but in chloraminated drinking waters. This is in stark contrast to the effect chloramine disinfection has on the formation of the regulated chloro/bromo-THMs and haloacetic acids, where chloramination significantly reduces their levels compared to chlorination. As a result, chloraminated drinking waters that have high bromide and iodide source waters will be targeted for this future quantitative occurrence work to determine whether the iodoacids commonly occur in high-iodide, chloraminated drinking waters and at what levels they are present. Ultimately, it will be important to know the levels at which these iodoacids occur in order to assess the potential for adverse environmental and human health risks. It should be noted that the iodoacids identified in this study were from a plant using chloramines only. For plants that have a significant free chlorine contact time before the addition of ammonia (to form chloramines), iodo-DBP formation may not be a problem.

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).

 

[tumor]

So guys, can I drink water from the tap in Toronto or not?You confusing me a lot with your reports and scientific stuff!

 

[Moonbear]

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

 

[Phobos]

So guys, can I drink water from the tap in Toronto or not?You confusing me a lot with your reports and scientific stuff!

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).

 

[Phobos]

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.

 

[Phobos]

It might depend on the source of your tap water. If it's municipally supplied, it should be fine.

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.

 

[Phobos]

Bottled water has to be purified too, but I don't know what methods various companies use.

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).

 

[Phobos]

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.

 

[Moonbear]

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).

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.

 

[Moonbear]

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.

Regarding the source waters and DBPs, the gist of what I got out of those articles I read yesterday is that a particular purification method doesn't always produce the same DBPs, it depends on what's in the source water. So, these studies on DBPs seemed to have identified something at two plants that is unique to their source water and purification method. It seems the results of these studies could be used then to improve water treatment processes to be more tailored to the composition of the source water to reduce DBPs.

What sizes are these DBPs? Would additional filtration steps remove them? For example, would one of those charcoal filters people put on their sink faucets do anything to remove them? What about the reverse osmosis filtration used by bottled water companies? Since some of these DBPs are only just being identified and standards are still be developed by EPA labs, bottled water companies probably aren't able to test for them any more than municipal supplies can.

Of course, if one spends too much time reading that Environmental Science Technologies journal, you'd be afraid to eat or drink anything. It's all a matter of putting it into reasonable perspective and realizing these studies are meant to help continue improving our water supply, not send us scurrying for bottled water. As Phobos pointed out, the health risk from pathogen contamination is of far greater and immediate concern than the much smaller risk from DBPs, so it's all a trade-off.

Phobos, are there processes being developed that would remove the contaminants that are converted into DBPs prior to chlorination (or any other method of disinfection)? Or at least removing some of the major culprits to reduce their overall levels?

 

[Phobos]

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).

Makes sense.

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.

Interesting. RO & ozone are very expensive treatment techniques. You're right that getting the chlorine taste out is a big factor is tap water is their source. For spring water, they probably focus on color & taste (dissolved stuff).

FWIW, ozonation creates its own DBPs...but far fewer (and different kinds...less toxic too, IIRC) than chlorination.

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.

Excellent point. That's a big reason why chlorine is used...it provides a great residual.

 

[Phobos]

Regarding the source waters and DBPs, the gist of what I got out of those articles I read yesterday is that a particular purification method doesn't always produce the same DBPs, it depends on what's in the source water. So, these studies on DBPs seemed to have identified something at two plants that is unique to their source water and purification method. It seems the results of these studies could be used then to improve water treatment processes to be more tailored to the composition of the source water to reduce DBPs.

You are correct. The source water makes all the difference. And not just from the obvious thing like how many pathogens there are (i.e., more pathogens requires more disinfectant which results in more DBPs) but also from the amount of stuff dissolved in the water. Usually organic matter is the big player because that is what the disinfectant reacts with to form the DBPs. The chlorine (Cl2 or HOCl) oxidizes the dissolved organic molecules just like it oxidizes (kills) pathogens. The chlorine then combines with the carbon, hydrogen, etc. to form DBPs like chloroform, etc. Dissolved organics have a double whammy in that they not only form DBPs, but they also require the use of more disinfectant because they use some of it up instead of having all the disinfectant focused on the pathogens. Filtration of these organics prior to disinfection is a big part of the treatment process.

So, each water treatment facility has to tailor its treatment process to its source water quality and its distribution requirements.

What sizes are these DBPs?

Varies.

Would additional filtration steps remove them?

Yes. (but this increases cost...another ever-present consideration/problem)

For example, would one of those charcoal filters people put on their sink faucets do anything to remove them?

Yes. "Activated carbon" is a cheap & effective way to deal with many (not all) DBPs.

What about the reverse osmosis filtration used by bottled water companies?

Yes. But it's much more expensive.

Since some of these DBPs are only just being identified and standards are still be developed by EPA labs, bottled water companies probably aren't able to test for them any more than municipal supplies can.

Correct. But they've certainly identified the big players.

Of course, if one spends too much time reading that Environmental Science Technologies journal, you'd be afraid to eat or drink anything. It's all a matter of putting it into reasonable perspective and realizing these studies are meant to help continue improving our water supply, not send us scurrying for bottled water. As Phobos pointed out, the health risk from pathogen contamination is of far greater and immediate concern than the much smaller risk from DBPs, so it's all a trade-off.

Absolutely. Drinking water treatment has been one of the most significant public health benefits in history. A perspective on relative risk is important (and difficult, since it goes against normal behavior). Without disinfection, there is an immediate (acute), high-risk of pathogens. There are many historical examples of deadly outbreaks from untreated drinking water. With disinfection, there is a much lower risk of health problems that might occur over a person's 70-80 year lifetime. I hesitate to put any numbers on that risk because it's specific to each situation.

Phobos, are there processes being developed that would remove the contaminants that are converted into DBPs prior to chlorination (or any other method of disinfection)? Or at least removing some of the major culprits to reduce their overall levels?

Yes (especially because the federal regulations are getting stricter) but usually I hear about existing technologies being refined to be more efficient. Existing techs with a good track record are more likely to be used on a public water supply than some new experimental tech. Drinking water treatment is not my current specialization, so I'm a little out of touch with the specifics on the latest techs.

Old school techs like filtration and coagulation/flocculation/sedimenation do a great job at reducing DBPs by removing the organic matter up-front (disinfection is typically the last step in the treatment process). There are limitations to those techniques and the stricter DBP regs are pushing those limits. So aside from making existing processes more efficient, there is a lot more attention on keeping the water source clean (watershed management) and looking into alternative disinfection methods like chloramines, ozone, etc. (which is probably the source of the articles cited toward the beginning of this topic).

 

[Kevinz]

Oh...I really do not want to take any risks with respect to health and also I suggest you friends to drink very pure water. Nowadays the water all over the world is being contaminated in one or the other way...

 

[mgb_phys]

A few bottled water companies outline their purification processes. Some start with municipal water and others spring water.

Dasani (coke-cola) water in the UK was just bottled tap water.
Unfortunately their filtering system added a few carcinogens at several times the legal limit.

http://news.bbc.co.uk/1/hi/business/3550063.stm
http://www.independent.co.uk/environment/pure-cokes-attempt-to-sell-tap-water-backfires-in-cancer-scare-567004.html

 

[jim mcnamara]

- do you mean Dasani? IS there an article about this?

 

[JorgeLobo]

Sure - we're all about to die.
The products of chlorine water treatment are of controlled to EPA standards. The alternative treatments have limited use. Filtration and ozone have limited use - they are expensive and have only initial effect - leave no residual "preservative " in water so bugs (esp. pseudomonads) will foul distribution.

 

[jim mcnamara]

No Jorge - I meant journal articles...

Newspapers are poor choices to cite except maybe to "incite" :)

I am not a fan of these kinds of PF threads - the ones trying to dispel clouds of misinformation, disinformation and partial fact mixed into a newpaper article...

It is an absolute no win deal IMO. If you'll notice
1. this is an old thread
2. the OP is long gone...

 

[JorgeLobo]

I offered no newspapers articles and was responding to the lack of factual data offered.

 

[Andy Resnick]

Is it safe to drink tap water?

NO! Water is poisonous! and can dissolve anything!

http://www.hsegroup.com/hse/text/water.htm

I prefer beer.

 

[Red Rum]

NO! Water is poisonous! and can dissolve anything!

http://www.hsegroup.com/hse/text/water.htm

I prefer beer.

Hear hear