# 55 Gal o' Water: How much Chlorine? (Y2K Prep) **URL:** \ **Category:** Factual Questions\ **Created:** [December 15, 1999, 2:25am UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525 "1999-12-15T02:25:00Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Stoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/stoid/32/272_2.png) [@Stoid](https://boards.straightdope.com/u/Stoid)\ **Post date:** [December 15, 1999, 2:25am UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525/1 "1999-12-15T02:25:00Z")
Subject sez it all. Doing my Y2K Prep, want to know how much chloring to add to my barrels to keep the water fresh but not poisonous. Thanks! * * * * * * I know it may LOOk like I’m not doing anything, but at the cellular level, I’m actually quite busy, ---
**Author:** ![Arken](https://avatars.discourse-cdn.com/v4/letter/a/dfb087/32.png) [@Arken](https://boards.straightdope.com/u/Arken)\ **Post date:** [December 15, 1999, 2:29am UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525/2 "1999-12-15T02:29:00Z")
Don’t add too much because when you pour it all out on January 1st after nothing happens, you’ll contaminate the soil. ---
**Author:** ![Stoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/stoid/32/272_2.png) [@Stoid](https://boards.straightdope.com/u/Stoid)\ **Post date:** [December 15, 1999, 2:33am UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525/3 "1999-12-15T02:33:00Z")
If nothing happens, I’ll keep it anyway because I live in Earthquake country and it’s simply prudent. I’ll change it every few months. ## I’d much rather look foolish because I prepared and nothing happened than look screwed or even dead because I was arrogant enough to think I knew what no one can know, and didn’t. * * * I know it may LOOk like I’m not doing anything, but at the cellular level, I’m actually quite busy, ---
**Author:** ![voguevixen](https://avatars.discourse-cdn.com/v4/letter/v/b5ac83/32.png) [@voguevixen](https://boards.straightdope.com/u/voguevixen)\ **Post date:** [December 15, 1999, 2:35am UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525/4 "1999-12-15T02:35:00Z")
I thought you were supposed to leave the cap off so that the chlorine evaporates? (No, I’m not gearing up for Y2K, I have to do this to make sourdough starter.) * * * “There’s a snake in my boot!” ---
**Author:** ![Stoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/stoid/32/272_2.png) [@Stoid](https://boards.straightdope.com/u/Stoid)\ **Post date:** [December 15, 1999, 2:37am UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525/5 "1999-12-15T02:37:00Z")
You pour some out and let the chlorine avaporate…but that would take an awfull long time if you had way too much chlorine to start with. I’ve heard something like “3 drops” per gallon, but that means 150 drops, which seems a bit silly. I’m sure there is a measurable amount for 55 gals. ---
**Author:** ![Arken](https://avatars.discourse-cdn.com/v4/letter/a/dfb087/32.png) [@Arken](https://boards.straightdope.com/u/Arken)\ **Post date:** [December 15, 1999, 2:40am UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525/6 "1999-12-15T02:40:00Z")
Okay, I’ll be serious now… Couldn’t you just buy a water purifier (like a brita pitcher) and pour the water from the drums into that before you used it for drinking purposes? ---
**Author:** ![APB9999](https://avatars.discourse-cdn.com/v4/letter/a/8e8cbc/32.png) [@APB9999](https://boards.straightdope.com/u/APB9999)\ **Post date:** [December 15, 1999, 2:46am UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525/7 "1999-12-15T02:46:00Z")
Good lord, why are you using chlorine? If you want to chemically treat water to make it potable go to a camping store and buy iodine tablets. The proper amount to mix is on the label. ---
**Author:** ![AWB](https://avatars.discourse-cdn.com/v4/letter/a/bb73d2/32.png) [@AWB](https://boards.straightdope.com/u/AWB)\ **Post date:** [December 15, 1999, 3:13am UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525/8 "1999-12-15T03:13:00Z")
Plus with the iodine, you’ll be filling your thyroid with non-radioactive iodine. That’ll keep the radioactive iodine from the nuclear-missiles-that-will-go-off-because-of-computer-bugs from contaminating your body. ---
**Author:** ![handy](https://avatars.discourse-cdn.com/v4/letter/h/b5a626/32.png) [@handy](https://boards.straightdope.com/u/handy)\ **Post date:** [December 15, 1999, 4:51pm UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525/9 "1999-12-15T16:51:00Z")
How doyou get water from a hot water heater? I got 40 gal, that should be enough, the stuff is probably sterile. I guess I can take it out from the drain on the bottom. What? No one thought of this? 🙂 ---
**Author:** ![Doctordec](https://avatars.discourse-cdn.com/v4/letter/d/cdc98d/32.png) [@Doctordec](https://boards.straightdope.com/u/Doctordec)\ **Post date:** [December 15, 1999, 5:33pm UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525/10 "1999-12-15T17:33:00Z")
On backpacking trips we used to use 2 drops per quart from a little bottle of bleach with an eyedropper in it. You can buy the bottle and dropper from a pharmacy. Iodine tabs are expensive a drop of bleach is nearly free and adds little or no taste. It has to sit for a few hours first before it’s safe to drink. 20 years ago the clorox bottle used to recommend the right abount on the label but they stopped putting it on. * * * “Hope is not a method” ---
**Author:** ![torq](https://avatars.discourse-cdn.com/v4/letter/t/dfb087/32.png) [@torq](https://boards.straightdope.com/u/torq)\ **Post date:** [December 16, 1999, 6:52am UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525/11 "1999-12-16T06:52:00Z")
Depending on the size of the dropper, a good rule of thumb is anywhere from 10-20 drops per ml; a teaspoon is about 5 ml. So 150 drops is somewhere between one and a half and three teaspoons. The people who wrote “3 drops per gallon” are probably expecting you to use a medicine dropper or something similar to that, which will be closer to the 10 drops per ml end of the scale. Iodine tablets are for cleaning up “found” water in streams or something like that. In theory you could use bleach for the same purposes (that’s more or less what your local drinking water treatment plant does), but iodine tablets are more convenient to carry around. However, you have to buy iodine tablets and you probably already HAVE bleach sitting around somewhere, so if you’re treating water to preserve it instead of clean it up after the fact, you may as well use bleach. The water in a water heater is NOT necessarily sterile (there are plenty of bacteria that can live at typical water heater temperatures); it’s also likely to have a fairly nasty taste. ---
**Author:** ![Doctordec](https://avatars.discourse-cdn.com/v4/letter/d/cdc98d/32.png) [@Doctordec](https://boards.straightdope.com/u/Doctordec)\ **Post date:** [December 15, 1999, 7:29pm UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525/12 "1999-12-15T19:29:00Z")
I forgot…Make sure you use the unscented bleach. I think the “fresh springtime scent” might taste worse and be more toxic than the bleach itself * * * “Hope is not a method” ---
**Author:** ![handy](https://avatars.discourse-cdn.com/v4/letter/h/b5a626/32.png) [@handy](https://boards.straightdope.com/u/handy)\ **Post date:** [December 16, 1999, 12:32am UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525/13 "1999-12-16T00:32:00Z")
Lets see, chlorine evaporates from the water too…we used to have a swimming pool & kept adding that stuff. If I have to drink it, hot water heater water would suffice for me…I don’t expect the gas to shut off, however, so I love hot water heater water. ---
**Author:** ![voguevixen](https://avatars.discourse-cdn.com/v4/letter/v/b5ac83/32.png) [@voguevixen](https://boards.straightdope.com/u/voguevixen)\ **Post date:** [December 16, 1999, 1:59am UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525/14 "1999-12-16T01:59:00Z")
So actually, that guy at the fastfood restaurant that put bleach in the ice machine was prepping for Y2K? ::fleeing:: * * * “There’s a snake in my boot!” ---
**Author:** ![handy](https://avatars.discourse-cdn.com/v4/letter/h/b5a626/32.png) [@handy](https://boards.straightdope.com/u/handy)\ **Post date:** [December 16, 1999, 5:19pm UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525/15 "1999-12-16T17:19:00Z")
vog, if you watch some Fox programs about getting caught on the job, there are quite a few other body fluids people put in public food… ---
**Author:** ![voguevixen](https://avatars.discourse-cdn.com/v4/letter/v/b5ac83/32.png) [@voguevixen](https://boards.straightdope.com/u/voguevixen)\ **Post date:** [December 16, 1999, 7:40pm UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525/16 "1999-12-16T19:40:00Z")
Is bleach a body fluid? * * * “There’s a snake in my boot!” ---
**Author:** ![Sofa\_King](https://avatars.discourse-cdn.com/v4/letter/s/58956e/32.png) [@Sofa\_King](https://boards.straightdope.com/u/Sofa_King)\ **Post date:** [December 16, 1999, 7:48pm UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525/17 "1999-12-16T19:48:00Z")
I recall it being 3-5 drops per gallon, but I think that figure was for purifying small amounts of water in the absence of a fire to boil it. My recommendation would be to purify it if you want to, then boil it over the smoking ruins of our civilization. After it cools to approximately 150 degrees, to prevent the biolab-mutated cholera from setting in, pour it into clean jars and store it in the ice-age glacier that’s flowing past your hovel. As for me? I’ll be drinking rum punch in the Carribean. ---
**Author:** ![system](https://global.discourse-cdn.com/straightdope/original/2X/e/e489c3b7d8fce19c4b355dd4fc3f88cc39c34b87.png) [@system](https://boards.straightdope.com/u/system)\ **Post date:** [December 16, 1999, 8:24pm UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525/18 "1999-12-16T20:24:00Z")
SofaKing was actually close: the amount to use of common laundry bleach is 5 drops to the gallon. As for how much to add for a drum, simply get a small measuring spoon and count the number of drops to fill it, then multiply appropriately. I figure 3 drops to a milliliter. ---
**Author:** ![Beadalin](https://avatars.discourse-cdn.com/v4/letter/b/3be4f8/32.png) [@Beadalin](https://boards.straightdope.com/u/Beadalin)\ **Post date:** [December 16, 1999, 9:10pm UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525/19 "1999-12-16T21:10:00Z")
I just found this in a project I am stuck with at work: Amount of Disinfectant Required for Each 100 Gallons of Water Laundry Bleach (5.25% Chlorine) = 3 cups\* Hypochloride Granules (70% Chlorine)= 2 ounces\*\* \*1 cup = 8-ounce measuring cup \*\*1 ounce = 2 heaping tablespoons of granules Source: Illinois Department of Public Health. Recommendations may vary from state to state. I hope that’s helpful. * * * “It says, I choo-choo-choose you. And it’s got a picture of a train.” – Ralph Wiggum ---
**Author:** ![Diceman](https://avatars.discourse-cdn.com/v4/letter/d/22d042/32.png) [@Diceman](https://boards.straightdope.com/u/Diceman)\ **Post date:** [December 17, 1999, 3:34pm UTC](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525/20 "1999-12-17T15:34:00Z")
Let’s see… 3 cups for 100 gallons equalls 1.65 cups for 55 gallons. Or 13.2 ounces. or 0.825 pints. or 26.4 tablespoons. or 79.2 teaspoons. (God, I love having a calculator that converts units. If anyone needs a length converted into Fermi’s or a temperature expressed on the Rankine scale, I’m your man :)) * * * “I had a feeling that in Hell there would be mushrooms.” -The Secret of Monkey Island [Next page](https://boards.straightdope.com/t/55-gal-o-water-how-much-chlorine-y2k-prep/5525.md?page=2)