4 ms·

London's water supply is pretty heavily chlorinated. Wouldn't that surpress bacterial activity?

Shivetya 9y ago
Going also to say that its likely many of the sanitary items are heavy in medical agents too
mseebach 9y ago
Is it really though? I've lived three places in London and made sourdoughs with tap water in all with no trouble. If it can't kill nacent yeast cultures, I wouldn't expect it to have many chances against sewer bacteria.
- collyw 9y ago
  Leaving water out for 24 hours will get rid of chlorine, so will boiling. Did your process involve either of those?
  - dt_rsp 9y ago
    Leaving it to stand works for chlorine, but not for chloramine, which a lot of tap water is treated with now instead. One would have to check with one's supplier.
    - collyw 9y ago
      I have been fermenting home made ginger beer either using filtered water, or water sat out for 24 hours. So probably not with chloramine in it.
- folknor 9y ago
  TLDR: It's not as simple as "apply bleach - things die." Yeast and bacteria are not the same thing. Practically, bleach doesn't kill yeast - if you try to kill fungus in your shower or on a wall with bleach, what that does is make it white. Which to us is a strong indication that it's dead, but it probably isn't. To clean fungus from your shower, for example, you need to mix vinegar and fresh bleach with cold water (of which the fumes can actually kill you as well) and use the solution properly, or use an industrial cleaning agent. Of course, someone who bleaches their shower will probably also wash it after (you should wash it _first_ before applying bleach), which might simply _physically remove_ most of the fungus from the surface. But depending on the solution you use, the fungus won't actually die. Note that the above is mostly true in household use of bleach, and not in correct use. Bleach _does_ kill most fungus if used correctly, but essentially noone does. Hot water significantly reduces the effectiveness of bleach, and so does using _more_ than you should, and also it loses effectiveness rapidly when it comes in contact with unclean surfaces, fat/organic material (which there is plenty of on your wall), etc, and also doesn't have a long shelf-life (20% effectiveness lost yearly if stored properly). It also needs 10-30 minutes of contact time, compared to some prepared solutions that are 90% effective in a few seconds, and 95% effective after 10 seconds.
  - michaelt 9y ago
    you need to mix vinegar and fresh bleach with cold water (of which the fumes can actually kill you as well) All the results I can find on Google for "bleach vinegar" say "Do not do this, chlorine gas is poison" - where can I learn more about how to do it properly, and why it works?
    - folknor 9y ago
      I believe it was Charlie Talley on this podcast: http://hwcdn.libsyn.com/p/3/9/0/390da96899933961/bbr03-29-07.mp3?c_id=1452161&expiration=1517859027&hwt=a5f7704d3178c89acade9ab7473b9bc4 http://hwcdn.libsyn.com/p/3/9/0/390da96899933961/bbr03-29-07... Essentially, you use the vinegar to adjust the pH of the water to the correct level - 8.0 - to get the right effect from the bleach (chlorine). Again, I have to stress what I said in my first post, that this _can be deadly for you_ if you don't use it correctly. http://podbay.fm/show/75092679/e/1175200200 http://podbay.fm/show/75092679/e/1175200200 might be a better link, I'm not sure. Interview starts around 9:30. Charlie is the inventor of Star San, a sanitizing solution used in breweries and by homebrewers. Which should make you skeptical, but don't be. He's essentially an expert who made a fantastic product, and only wants to help. In the podcast he outlines how to use normal household products as replacements for his products. I haven't listened to it since 2012 or so, so if I am mistaken about the source, please let me know and I'll find the correct source of the information in my original post.
- Reason077 9y ago
  "Is it really though? I've lived three places in London and made sourdoughs with tap water in all with no trouble." That's interesting. I haven't made real sourdough for a long time, but I do bake bagels, bread, and pizza dough pretty regularly. While London tap water does work, I've noticed on many occasions that the dough rises a lot faster and requires much less yeast when using filtered or bottled water (I usually use the cheap Tesco Ashbeck water that you buy in big 5L bottles) compared to using straight tap water. But whether this is due to chlorination or other factors (London water is notoriously "hard", too) I'm not sure.
dx034 9y ago
I doubt that. To me, London tap water never tasts like chlorine, I suspect it's chlorinated much less than most tap water in the US.
- narag 9y ago
  I thought that you use fluorine in the USA instead of chlorine.
  - CapitalistCartr 9y ago
    Fluorine is an additive to prevent teeth decay; chlorine or chloramine is to prevent disease in the water. Both are routinely added in the US.
    - joering2 9y ago
      Exactly. Worth adding if you live in USA and have a chance to visit your local water treatment plantation (they always welcome visitors), go see their state-of-the-art system for treating water. What I didn't know is that there is very complicated system that forbids flushing water back into the central system to poison it. The idea is that a terrorist could plug themselves into pipe and inject poison that will travel back to the treatment plant and obviously from there go to each sink, sort of like an online virus :) very cool stuff.
      - gambiting 9y ago
        Is it really because of terrorists? Or because it's simply common sense?
      - Spooky23 9y ago
        That’s probably just the justification for the grant used to get federal money for the system. The reality is that if you have people equipped to poison the water supply, they will be able to. Most water systems have multiple interconnects with neighboring systems to allow exchange of treated water. Security is typically nonexistent. The good news is that that type of attack isn’t particularly useful as a terrorist event and is likely low risk.

Going also to say that its likely many of the sanitary items are heavy in medical agents too

Is it really though? I've lived three places in London and made sourdoughs with tap water in all with no trouble. If it can't kill nacent yeast cultures, I wouldn't expect it to have many chances against sewer bacteria.

collyw 9y ago
Leaving water out for 24 hours will get rid of chlorine, so will boiling. Did your process involve either of those?
- dt_rsp 9y ago
  Leaving it to stand works for chlorine, but not for chloramine, which a lot of tap water is treated with now instead. One would have to check with one's supplier.
  - collyw 9y ago
    I have been fermenting home made ginger beer either using filtered water, or water sat out for 24 hours. So probably not with chloramine in it.
folknor 9y ago
TLDR: It's not as simple as "apply bleach - things die." Yeast and bacteria are not the same thing. Practically, bleach doesn't kill yeast - if you try to kill fungus in your shower or on a wall with bleach, what that does is make it white. Which to us is a strong indication that it's dead, but it probably isn't. To clean fungus from your shower, for example, you need to mix vinegar and fresh bleach with cold water (of which the fumes can actually kill you as well) and use the solution properly, or use an industrial cleaning agent. Of course, someone who bleaches their shower will probably also wash it after (you should wash it _first_ before applying bleach), which might simply _physically remove_ most of the fungus from the surface. But depending on the solution you use, the fungus won't actually die. Note that the above is mostly true in household use of bleach, and not in correct use. Bleach _does_ kill most fungus if used correctly, but essentially noone does. Hot water significantly reduces the effectiveness of bleach, and so does using _more_ than you should, and also it loses effectiveness rapidly when it comes in contact with unclean surfaces, fat/organic material (which there is plenty of on your wall), etc, and also doesn't have a long shelf-life (20% effectiveness lost yearly if stored properly). It also needs 10-30 minutes of contact time, compared to some prepared solutions that are 90% effective in a few seconds, and 95% effective after 10 seconds.
- michaelt 9y ago
  you need to mix vinegar and fresh bleach with cold water (of which the fumes can actually kill you as well) All the results I can find on Google for "bleach vinegar" say "Do not do this, chlorine gas is poison" - where can I learn more about how to do it properly, and why it works?
  - folknor 9y ago
    I believe it was Charlie Talley on this podcast: http://hwcdn.libsyn.com/p/3/9/0/390da96899933961/bbr03-29-07.mp3?c_id=1452161&expiration=1517859027&hwt=a5f7704d3178c89acade9ab7473b9bc4 http://hwcdn.libsyn.com/p/3/9/0/390da96899933961/bbr03-29-07... Essentially, you use the vinegar to adjust the pH of the water to the correct level - 8.0 - to get the right effect from the bleach (chlorine). Again, I have to stress what I said in my first post, that this _can be deadly for you_ if you don't use it correctly. http://podbay.fm/show/75092679/e/1175200200 http://podbay.fm/show/75092679/e/1175200200 might be a better link, I'm not sure. Interview starts around 9:30. Charlie is the inventor of Star San, a sanitizing solution used in breweries and by homebrewers. Which should make you skeptical, but don't be. He's essentially an expert who made a fantastic product, and only wants to help. In the podcast he outlines how to use normal household products as replacements for his products. I haven't listened to it since 2012 or so, so if I am mistaken about the source, please let me know and I'll find the correct source of the information in my original post.
Reason077 9y ago
"Is it really though? I've lived three places in London and made sourdoughs with tap water in all with no trouble." That's interesting. I haven't made real sourdough for a long time, but I do bake bagels, bread, and pizza dough pretty regularly. While London tap water does work, I've noticed on many occasions that the dough rises a lot faster and requires much less yeast when using filtered or bottled water (I usually use the cheap Tesco Ashbeck water that you buy in big 5L bottles) compared to using straight tap water. But whether this is due to chlorination or other factors (London water is notoriously "hard", too) I'm not sure.

dx034 9y ago

I doubt that. To me, London tap water never tasts like chlorine, I suspect it's chlorinated much less than most tap water in the US.

narag 9y ago
I thought that you use fluorine in the USA instead of chlorine.
- CapitalistCartr 9y ago
  Fluorine is an additive to prevent teeth decay; chlorine or chloramine is to prevent disease in the water. Both are routinely added in the US.
  - joering2 9y ago
    Exactly. Worth adding if you live in USA and have a chance to visit your local water treatment plantation (they always welcome visitors), go see their state-of-the-art system for treating water. What I didn't know is that there is very complicated system that forbids flushing water back into the central system to poison it. The idea is that a terrorist could plug themselves into pipe and inject poison that will travel back to the treatment plant and obviously from there go to each sink, sort of like an online virus :) very cool stuff.
    - gambiting 9y ago
      Is it really because of terrorists? Or because it's simply common sense?
    - Spooky23 9y ago
      That’s probably just the justification for the grant used to get federal money for the system. The reality is that if you have people equipped to poison the water supply, they will be able to. Most water systems have multiple interconnects with neighboring systems to allow exchange of treated water. Security is typically nonexistent. The good news is that that type of attack isn’t particularly useful as a terrorist event and is likely low risk.