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#1
Old 04-20-2009, 02:32 PM
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Disaster strikes. How do I make swimming pool water drinkable?

Imagine some great disaster strikes (asteroid, solar flare, whatever) and shuts down the power grid and greatly disables road travel. Water service is unavailable because of the lack of power. You can survive on only the things within your walking distance. Your neighborhood has a community swimming pool and it is the only viable water source.

How would you go about making the swimming pool water drinkable? As for equipment, assume this is a normal, surban neighborhood. The normal household items would be available (pots, pans, garage tools, etc). There would be a plentiful supply of wood around for fuel. How could you create a neighborhood water purification system from normal household items?
#2
Old 04-20-2009, 02:39 PM
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All that cholrine and urine? I wouldn't drink it unless it were distilled.

The easiest way? Figure out how to boil the water where there is no wind. Then, take a large sheet of glass, or metal and put it above the pot of water, so the flat surface is facing the water and the sheet is angled at about 45°.

Get the water boiling. When the steam hits the glass/metal it will condense. Put a pot under the low end of the sheet to catch the drippins. That'll probably be good enough to drink. And probably as good as you'll do in a post apocolyptic scenario.
#3
Old 04-20-2009, 02:57 PM
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Unless you've really overchlorinated it, it is already drinkable. The chlorine should have knocked out any fecal bacteria of significance (significant virulence and significant concentration of said bacteria), & dilute urine is not harmful.
#4
Old 04-20-2009, 03:01 PM
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I agree with the distilling as both the easiest and safest way to make it drinkable. If you're in a relatively sunny and warm climate, you could even use the sun to distill the water which may be a good idea if you need to conserve firewood for some reason or another.
#5
Old 04-20-2009, 03:04 PM
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Originally Posted by Qadgop the Mercotan View Post
Unless you've really overchlorinated it, it is already drinkable. The chlorine should have knocked out any fecal bacteria of significance (significant virulence and significant concentration of said bacteria), & dilute urine is not harmful.
Really? I hadn't realized that. Well, that's no fun. So imagine that I'm not sure how the pool is treated. Maybe it's treated with salt. Or maybe I don't know if it's been shocked recently. Actually, since the power has been out for a week and the pumps aren't running, the pool has turned a lovely shade of slimy green and smells awful.
#6
Old 04-20-2009, 03:07 PM
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And if you don't like the chlorine, just wait a while. If it were me, I'd fill every container I could; capping some for longer storage and leaving a few uncovered to naturally dechlorinate for short-term use. Becuase eventually the pool will dissapate all it's chlorine and sooner or later get nasty.
#7
Old 04-20-2009, 03:11 PM
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Wouldn't heating the water to boiling point get rid of most of the chlorine, and kill and bugs that the chlorine hadn't killed, so that water would be safe to drink (if not all that tasty)?
#8
Old 04-20-2009, 03:22 PM
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Chlorine will evaporate out of a pool in a matter of a day or two - pools need a feeder to maintain an active supply. Furthermore, sunlight denatures the chlorine. When I managed an apartment complex swimming pool, our chlorine would reach 0 by mid-afternoon without a feeder to keep adding more. The amount of chlorine in a pool (assuming you're within the 3-5 ppm required by health regulations) poses no risk to you, even if you drink the water.

The problem is as others have pointed out - within a week, you could be growing algae and mosquitoes.

My recommendation would be to keep a healthy supply of chlorine around (granules, tablets or bleach - for pool owners, these are household supplies) and treat the water that way. I'm not sure the exact amounts needed to make water safe for drinking, but it doesn't take very much (10-20 parts per million is used for "shocking" the water). If you know basic algebra, you can use the instructions on the chlorine container to calculate the dosage. Dose the water about a day before you need it and leave it open in the sun. It may taste awful, but it will be safe.

The military has water treatment tablets that might be even better, but you specified household supplies.
#9
Old 04-20-2009, 03:51 PM
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Household bleach is chlorine.
#10
Old 04-20-2009, 03:53 PM
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What if the pool is treated with bromine instead of chlorine?
#11
Old 04-20-2009, 04:09 PM
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These dont sound like likely scenarios to me. In the event of a disaster the first things stolen or hoarded will be chlorine and bottled water. You wont be able to walk into the local pool store and get chlorine or bleach.

Distilling by using heat or even evaporation is how people in extreme circumstances survive. By the time you spend two hours walking to the pool store only to find it empty or some guy with a shotgun telling you to get lost, your neighbor has already started siphoning and distilling your pool water to keep his family from dehydrating. He wont share any with you. Heck, he'll probably keep people away from the pool with a shotgun too.

Ditilling is safe and simple, but takes time. Perhaps I have a more realistic view of the average suburbanite, but I wouldnt be surprised that giving the task of turning green water into drinking water via chemicals to a random guy will just lead to either unsafe water or chlorine poisoning.

This is one of my pet peeves. When fiction writers describe disasters it seems everyone is a McGyver and everyone has a can-do selfless spirit. Thats the exception, not the rule. In situations where water or food is scarce, guns and violence rule, not quick thinking and community spirit.

Last edited by HorseloverFat; 04-20-2009 at 04:11 PM.
#12
Old 04-20-2009, 04:47 PM
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Bleach (the washing kind), at least in my house, doesn't have enough concentration. You'd be pouring inordinate ammounts, even compared to liquid chlorine.
#13
Old 04-20-2009, 04:51 PM
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I just took the CERT classes in Los Angeles (cert-la.com), run by the fire dept, which teach what to do in emergencies.

The instructor said very clearly that there is nothing you can do to swimming pool water to make it safe to drink.

The idea is to stock up with supplies ahead of time. Especially water.
#14
Old 04-20-2009, 04:57 PM
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Quote:
Originally Posted by HorseloverFat View Post
These dont sound like likely scenarios to me. In the event of a disaster the first things stolen or hoarded will be chlorine and bottled water. You wont be able to walk into the local pool store and get chlorine or bleach.

Distilling by using heat or even evaporation is how people in extreme circumstances survive. By the time you spend two hours walking to the pool store only to find it empty or some guy with a shotgun telling you to get lost, your neighbor has already started siphoning and distilling your pool water to keep his family from dehydrating. He wont share any with you. Heck, he'll probably keep people away from the pool with a shotgun too.
If your neighbor who doesn't have a pool is siphoning off your pool water, where is he storing it? If he doesn't have a pool himself the only place to put your pool water is in your pool.

You don't need to distill pool water to make it safe to drink. It's already safe to drink. It's not like it's going to turn into a swamp in a day, and even if it has algae the algae isn't toxic. What you have to worry about is animal feces and dead animals.

So the most important thing is to put a cover over the pool to keep out leaves and dirt and animals and minimize evaporation. But the amount of water needed for drinking purposes is very small compared to the volume of a swimming pool.

And if you have household bleach you don't need to sanitize the whole pool, just the stuff you're going to drink that day. You haul out a jug of water, put in a few drops of bleach, and leave the jug to sit for a day, and drink it the next day.
#15
Old 04-20-2009, 04:57 PM
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So even if the water goes bad why couldn't you just hang a tarp over a section (all) of the pool? Raise the center of the tarp so it's tent-shaped and manage the edges so that the water that condenses runs down to one of the corners and into a collection vessle?

And drink on that while you hunt down a Fresnel lens (from the back window of someone's conversion van) or other magnifying lens to create a solar-powered water boiling thing.

And then head for the hills while society completely disintegrates.
#16
Old 04-20-2009, 04:57 PM
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I'm not so sure about this. At Caltech, we were told (by those who have to think about these things) that in the case of a severe earthquake, much of our drinking water would be dechlorinated water from the gym's swimming pool.

Quote:
Originally Posted by filmyak View Post
I just took the CERT classes in Los Angeles (cert-la.com), run by the fire dept, which teach what to do in emergencies.

The instructor said very clearly that there is nothing you can do to swimming pool water to make it safe to drink.

The idea is to stock up with supplies ahead of time. Especially water.
#17
Old 04-20-2009, 05:27 PM
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First, imagine this is the community pool and all neighbors are working together to make it drinkable. If it's drinkable as is, then they'd just come with buckets. If it needs to be processed, the neighbors would work together to make it drinkable.

Second, I would be very concerned about the non-chlorine chemicals in the water. I know our community pool uses salts instead of chlorine. I would imagine the salt alone would make it unsuitable in terms of drinking water regardless if there were any bugs in it.

Perhaps the fire dept above said pool water was unusable because it would take more effort than would be an appropriate in a normal disaster. That is, in a normal disaster the authorities will come by relatively quickly and distribute aid. But if it was clear that aid was not coming in the foreseeable future, the pool water may mean the difference between life and death.

So say it's been a week. The last of the suitable water left in the houses (water heater, toilet tank, etc) was gone 3 days ago. No one thought to store water because they all thought the authorities would be by with aid, which is not coming. Now you and your neighbors are looking at the only water source: 20000+ gallons of slimy pool water with an unknown amount of unknown pool chemicals. You will die if you don't get water soon. Is there a way to make that water safe to drink?
#18
Old 04-20-2009, 05:35 PM
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Originally Posted by brewha View Post
The easiest way? Figure out how to boil the water where there is no wind. Then, take a large sheet of glass, or metal and put it above the pot of water, so the flat surface is facing the water and the sheet is angled at about 45°.
No. If there's no wind, eventually your surface will heat up and water will no longer condense. What you need is a large flexible hose, some rope, and a blanket. And some wind. Coil the hose so the input is at the top and the output at the bottom. Hang the coiled hose from a tree or something. Soak the blanket (in water or urine) and drape it over the coil. The steam from your kettle or whatever goes in the top of the coil and the energy of first heating then evaporating the water in the wet blanket cools the steam giving you potable water out the other end of the coil.
#19
Old 04-20-2009, 05:43 PM
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Originally Posted by filmore View Post
Is there a way to make that water safe to drink?
You can just boil it. This is why everyone in China drinks tea.
#20
Old 04-20-2009, 05:53 PM
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Originally Posted by gotpasswords View Post
What if the pool is treated with bromine instead of chlorine?
Bromine is virtually identical to chlorine in most respects. You need about twice as much of it for the same sanitizing effect, though.

The main reason bromine is used instead of chlorine is that it won't form chloramines, which are the actual compounds that cause most of the classic chlorine smell and irritation.
#21
Old 04-20-2009, 06:53 PM
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I'd say get one of those hiking water filters. Start by runing it through a Brita- type, then one of the hiking filters, then I think you'd be fine. Or a Brita then a Steri-pen.

The problem with boiling is that you likely have less fuel than water, and fire is a danger.

A water filter is an excellent survival tool.
#22
Old 04-20-2009, 07:28 PM
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What's with everyone wanting to distill the water? How will you know you're not distilling out chlorine?
In beermaking, if you accidentally get chlorine (from sanitization) into your wort (unfermented beer), you are generally instructed to re-boil the wort in order to boil off the chlorine. See C. Papazian The Joy of Home Brewing
#23
Old 04-20-2009, 07:34 PM
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Originally Posted by ArmenE View Post
What's with everyone wanting to distill the water? How will you know you're not distilling out chlorine?
Because it doesn't matter. If you somehow wind up with chlorine in your distillate, you just let it sit a day or two and the problem will solve itself. In the meantime, the distillation has gotten rid of all bacteria, viruses, protists and most other potential nasties, such as fecal material, decay products or urine and other unwanted chemicals. If you need potable water, it's THE simplest and most effective method of producing it from any water source. Even from a septic tank, if it came to that.
#24
Old 04-20-2009, 07:50 PM
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First step is to stop shitting into your pool.

With that taken care of, the water's really not that bad. How do you think animals live? Or pre-fire humans? No, there wasn't some antibacterial saliva or activated-charcoal throat-pouch that got lost to evolution. (Although you do need to start training your system a bit so that it won't shit itself at the first whiff of a bacterium. But even if you get some diarrhea, that's not quite the same as a serious illness.)

Quote:
Originally Posted by Lemur866 View Post
You don't need to distill pool water to make it safe to drink. It's already safe to drink. It's not like it's going to turn into a swamp in a day, and even if it has algae the algae isn't toxic. What you have to worry about is animal feces and dead animals.
#25
Old 04-20-2009, 07:55 PM
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Originally Posted by HorseloverFat View Post
Distilling by using heat or even evaporation is how people in extreme circumstances survive.
How would you go about distilling water with ambient evaporation?

Quote:
So even if the water goes bad why couldn't you just hang a tarp over a section (all) of the pool? Raise the center of the tarp so it's tent-shaped and manage the edges so that the water that condenses runs down to one of the corners and into a collection vessle?
That sounded clever at first, but the sun's just going to heat up the tarp way above ambient and nothing will condense on it.
#26
Old 04-20-2009, 07:55 PM
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Originally Posted by Ají de Gallina View Post
Bleach (the washing kind), at least in my house, doesn't have enough concentration. You'd be pouring inordinate ammounts, even compared to liquid chlorine.
Baloney.

I don't recall the exact amount, but for household bleach, its like DROPS of it per gallon of water to make nasty (biologically)water safe. So, you are talking tablespoons/small fractions of a cup for something in the hundred gallon range. Which means a gallon of house hold bleach will treat thousands of gallons of water off the top of my head.

If you've got nasty water, some household bleach, and can stomach icky tasting water, your good to go as far as I know.

Last edited by billfish678; 04-20-2009 at 07:57 PM.
#27
Old 04-20-2009, 08:05 PM
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Originally Posted by Quartz View Post
No. If there's no wind, eventually your surface will heat up and water will no longer condense. What you need is a large flexible hose, some rope, and a blanket. And some wind. Coil the hose so the input is at the top and the output at the bottom. Hang the coiled hose from a tree or something. Soak the blanket (in water or urine) and drape it over the coil. The steam from your kettle or whatever goes in the top of the coil and the energy of first heating then evaporating the water in the wet blanket cools the steam giving you potable water out the other end of the coil.
No? Just no? That's funny. Allow me to respond in kind.
Yes.
I don't recall specifying the size of the sheet. Do you really believe that you have to have wind to have heat transfer? Yes, wind increases it, but if the sheet were big enough, it would stay cool enough for condensation - even in still air.
#28
Old 04-20-2009, 08:33 PM
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If there's wind, the main way that wind will cool the condensation sheet is by... guess what... evaporating the water off it. I still don't get how it works. To do it right, you'd have to attach a cooling loop using dirty water or an evaporation system using dirty water.

But, I guess, a very large sheet and no wind (and no sun) may work.

Last edited by Alex_Dubinsky; 04-20-2009 at 08:37 PM.
#29
Old 04-21-2009, 12:50 AM
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Originally Posted by brewha View Post
]but if the sheet were big enough, it would stay cool enough for condensation - even in still air.
I'm confused too. Your idea is workable, but hideously inefficient. Your sheet of whatever would have to be very large and conductive, and you would lose a lot of vapor. An enclosed system is easier to make -- a pot with a lid, a brick on top to keep it tight, and a hole to let steam out into a cooling tube of some sort.

As for the solar still idea, it's workable, but very slow and it doesn't take advantage of the pool. Say the ambient temperature is 80 degrees. Disregarding solar effects (that would make the sheet hotter and the pool cooler), the sheet of whatever will be 80 degrees. The water will be 80 degrees. Water that evaporates from the pool would have no reason to condense, just like trees and benches and other things don't condense water out of the air.

Now, as the sun set, the temperature of the sheet would drop faster than that of the earth and water system (the pool), so you would get some condensation (which is why dew forms). The energy to power a still of any sort has to come from somewhere, because they work by converting the water to vapor and back, so you have to maintain a temperature difference between the ends of the still system, and the higher the difference the more water vapor you will capture. The day/night cycle is a way to get this for "free", but it's really really slow. A lens or solar collector would help, but it's still going to be very slow -- a pool has incredible thermal mass.

I don't think that the amount of water you would get from a passive temperature cycle system would be much compared to the ease and availability of just treating and drinking the water, and you wouldn't likely be capturing an appreciable amount of pool water unless it was totally enclosed, as water vapor from the pool would distribute rapidly into the atmosphere -- I am guessing the ambient humidity isn't going to be much higher near the pool. You could generate water by solar still from plant matter and such just as easily as from a pool.

On a side note, a still with a long enough coil will cool steam back to water, and there's no need for wet blankets or other stuff to increase cooling. The tube will be closer to ambient at one end as it sheds heat to the air, and that will be sufficient to condense the steam back into pure water.

I think your best bets in a survival situation are just to boil the water, chemically treat it, or to filter it. Pool water will remain drinkable for at least days. Running water through a tightly woven cloth and then boiling for a period of time is enough to sterilize the water, and there are not high levels of chemicals in pool water -- it's a given that you will ingest some pool water when swimming. You can do the same things with river water or well water as well. Distilling the water is just overkill.
#30
Old 04-21-2009, 01:02 AM
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The biggest advantage of a solar-based process is that it’s simple. I present the Watercone. In a true emergency, you could jury-rig a similar device relatively easily.

It may be slow (not too slow, really), but it would allow you to use your fuel for cooking food. It also works on saltwater.
#31
Old 04-21-2009, 01:24 AM
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Originally Posted by Alex_Dubinsky View Post
That sounded clever at first, but the sun's just going to heat up the tarp way above ambient and nothing will condense on it.
The water vapor will stick to the tarp and to itself and will trickle down to your edges. I've seen it done even in very hot places like Florida. You can use this to collect water from green vegatation as well. You don't even need to start with water. Fill a hole with fresh green leaves and grass and cover it with plastic. Weigh down the middle with a rock and underneath put a jar to collect the drippings. It can fill a canteen in a day easily.
#32
Old 04-21-2009, 08:40 AM
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To repeat: A little chlorine is perfectly healthy. What do you think they do at the plant that makes your tapwater? (And, again, most bottled water is just tapwater in a bottle).
And chlorine goes away all by itself, so even if there's a little too much to begin with, it will get to drinkable levels soon.

The only problem comes when all the chlorine is used up. Then you start worrying about contamination. This doesn't mean it turns instantly deadly, but starts increasing the chances of getting the runs or something. Hint: don't crap in the pool, or wash your hands in the pool after crapping, or let animals into the pool, etc. Eventually, with just standing water, it might start getting funky with algae and what-not in there; it still might be perfectly healthy, but then again might not.

So at some point, depending on how funky it is and how much fuel you have, you might want to start boiling the water. Get a good rolling boil (for a couple minutes for maximum protection), let it cool and drink.

Active distillation is way, way, overkill and a huge waste of fuel. Solar distillation is fine, but not real high volume; depending on what materials you have, you might be better off spending the time looking for fuel instead of building a solar still.
#33
Old 04-21-2009, 09:54 PM
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Originally Posted by garygnu View Post
I present the Watercone.
Ok, I can see how a clear cover and a black water vessel could work. Are the pool tarps also clear?

I guess this answer my other question: if solar distilling is so freakin easy, why didn't ships use it for thousands of years. Apparently, it's because they didn't have transparent plastic film.
#34
Old 04-22-2009, 12:20 AM
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Unless there are lots of kids and the pool is poorly maintained, your typical pool will have between 2 and 3 parts per million of total chlorine, the vast majority of which should be free available chlorine. If you have a ton of people or kids in the pool a lot, and the chemicals get neglected, you could have mostly combined chlorine, and I don't know if I'd want to drink that.

As for chlorine dissipation, most pool owners now use tabs, which contain some cyanuric acid. While this is a good thing for pool owners, it's not so good for people who want to drink the water, as it protects the chlorine from the UV rays, somewhat, so the chlorine will stick around a bit longer.

I'm not a chemist, even though as a pool owner I sometimes feel like one, but these are rough averages for some of the common attributes of a well balanced pool, so if anyone sees anything that would make it undrinkable, chime in:

Chemicals, in parts per million:
Chlorine: 2-3
Cyanuric acid: 40-50
Alkalinity: 120
Calcium hardness: 250

Most pools also have a ph of between 7.2 and 7.6 or so, which is definitely not a problem.

A couple of things to watch for, superchlorinating (what is sometimes called "shock", although shock comes in non-chlorine forms as well, so I don't use that term here), which is done to free up combined chlorine. In those cases, the chlorine level can easily reach 30 ppm or even higher. Also, when a pool gets too alkaline, pool owners pour in muriatic acid. While I'm sure that dilutes pretty quickly, you certainly want to wait many hours after an application, as that is some of the nastiest stuff around. Finally, without a test kit, it's going to be really hard to tell whether the pool is well balanced, or deadly as hell, just by looking at it. There are many ways of achieving clear, sparkling water, some of which aren't really conducive to making it safe for drinking.

There are a variety of other chemicals that are used for various purposes (sometimes simply because the pool supplier said it was needed), but the above are the basics that you can expect in most pools.

I'll let people who know about those things actually answer whether this all means that you can drink it or not.
#35
Old 04-22-2009, 12:28 AM
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I forgot to mention the salt issue mentioned above. If the pool uses a salt chlorination system (not common, but not particular rare either), the water will indeed have salt in it, but typically in the 2500 ppm range, which is probably 5-7% of the concentration found in ocean water. You can also tell if they have this system pretty easily, as it is typically inserted into the visible plumbing near the pump.
#36
Old 04-22-2009, 12:28 PM
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Originally Posted by DMC View Post
Also, when a pool gets too alkaline, pool owners pour in muriatic acid. While I'm sure that dilutes pretty quickly, you certainly want to wait many hours after an application, as that is some of the nastiest stuff around.
Your stomach is already full of muriatic acid. It does dilute extremely rapidly.

Salt water chlorinators are just generating on site the same pool chemical(sodium hypochlorite in this case) that is found in most common swimming pool chlorinators. Since the necessary sodium chloride amount in the pool is low, I don't see a salt chlorinator being a deal breaker in terms of drinkable water.

The acute oral LD50 for cyanuric acid is listed as 3400 mg/kg [Mouse]. I'm not a toxicologist, but at 40-50 ppm that doesn't bother me.

I'd suck down a glass of eau de pool if I was thirsty enough.
#37
Old 04-22-2009, 01:56 PM
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Originally Posted by Solfy View Post
Your stomach is already full of muriatic acid. It does dilute extremely rapidly.
Your stomach is designed to contain and withstand it; the path to get it there, however, is not. Ask anyone with gastric reflux disease.
#38
Old 04-22-2009, 02:09 PM
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Originally Posted by Q.E.D. View Post
Your stomach is designed to contain and withstand it; the path to get it there, however, is not. Ask anyone with gastric reflux disease.
True enough, but how many gallons of straight muractic are added to how many gallons of pool water?

Good grief, folks are acting like pool water and diluted chlorine are the devils own brew.

If the apoolcalipse comes, trust me, funky pool water with icky chemicals is gonna be the least of your worries.
#39
Old 04-22-2009, 02:39 PM
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Originally Posted by billfish678 View Post
If the apoolcalipse comes, trust me, funky pool water with icky chemicals is gonna be the least of your worries.
True enough. 3/4 of the planet's population survives on water that's less clean/safe than your average pool.
#40
Old 04-22-2009, 02:44 PM
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Not to mention pools are made for swimming in, which means you're going to get it in your eyes, in your nose (maybe sinuses), in your mouth, in your ears, all over your skin, and you are probably going to swallow a little at some point. Admittedly pool water does kill a few people when they get it into their lungs, but I'm not sure that's the pool chemicals at work.
#41
Old 04-22-2009, 02:48 PM
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Sure it is--for certain values of the word "chemical".
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Old 04-22-2009, 04:05 PM
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Originally Posted by Q.E.D. View Post
Your stomach is designed to contain and withstand it; the path to get it there, however, is not. Ask anyone with gastric reflux disease.
Let's assume an in-ground pool with a size of 25'x45' and an average depth of 5'. It holds approximately 42,187 gallons of water. Let's assume the pH needed to be adjusted with 1 gallon of 10% HCl. You've just put a tenth of a gallon of acid in over 42,000 gallons of water. Since the pH was already high, the acid will react rapidly with basic species in the water to bring the average pH down to neutral in short order (the reaction rates are extremely rapid), meaning you no longer have acid. You've got almost neutral water with a tiny concentration of salts. I don't think your throat is even going to tickle.
#43
Old 04-22-2009, 04:08 PM
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If the pH is off, the chlorine won't do diddly.

So, you need a proper pH range and chlorine.
#44
Old 04-22-2009, 07:23 PM
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While I agree that the muriatic acid dilutes quickly, it's not quite as quick as it is being made out to be. Again, not being a chemist, I have no idea if the stuff I pour in my pool is some special formulation or not, but it has a consistency a bit thicker than water, and depending on where it is poured, can certainly stay fairly concentrated in a small area for a short amount of time. In fact, it is typically recommended to only add a quart at a time, and wait 12 hours before adding any more and/or testing pH levels, even if your calculations tell you that you need gallons to get the pH back in line.
#45
Old 04-22-2009, 07:30 PM
DMC DMC is offline
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Originally Posted by billfish678 View Post
True enough, but how many gallons of straight muractic are added to how many gallons of pool water?
Typically, even if your pH is a bit above 8.0, a smaller pool (15k gallon range or so) will only need a quart or two to get back in line. The most I've heard of is a ratio of about 1 gallon per 2000 gallons of water, although you'll rarely see that as a recommendation by any experts. You see this happen because someone read something on some message board stating that it was a way to "shock" the scale from your pool. The problem is it also drops the pH like a rock, and things like pool heaters aren't real happy about that.

Last edited by DMC; 04-22-2009 at 07:30 PM.
#46
Old 04-22-2009, 09:43 PM
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Quote:
Originally Posted by DMC View Post
While I agree that the muriatic acid dilutes quickly, it's not quite as quick as it is being made out to be. Again, not being a chemist, I have no idea if the stuff I pour in my pool is some special formulation or not, but it has a consistency a bit thicker than water, and depending on where it is poured, can certainly stay fairly concentrated in a small area for a short amount of time. In fact, it is typically recommended to only add a quart at a time, and wait 12 hours before adding any more and/or testing pH levels, even if your calculations tell you that you need gallons to get the pH back in line.
Then we must post a message on the swimming pool: CAUTION: Stir well before drinking.
And yeah, acid will be slightly more viscous than water, but even 12N is nicely mixable. You're waiting that long because you want an accurate pH reading for the whole pool, not because there's a ball of acid lurking in the middle. (if it helps, I am a chemist, but I leave the swimming pool treatments to my colleagues out back where the test pools are)

Last edited by Solfy; 04-22-2009 at 09:45 PM.
#47
Old 04-22-2009, 10:13 PM
DMC DMC is offline
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Originally Posted by Solfy View Post
Then we must post a message on the swimming pool: CAUTION: Stir well before drinking.
And yeah, acid will be slightly more viscous than water, but even 12N is nicely mixable. You're waiting that long because you want an accurate pH reading for the whole pool, not because there's a ball of acid lurking in the middle. (if it helps, I am a chemist, but I leave the swimming pool treatments to my colleagues out back where the test pools are)
Can I hit you up with chemical questions that I can't get answered at my local pool supply place?
#48
Old 04-22-2009, 10:44 PM
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Quote:
Originally Posted by billfish678 View Post
Baloney.

I don't recall the exact amount, but for household bleach, its like DROPS of it per gallon of water to make nasty (biologically)water safe. So, you are talking tablespoons/small fractions of a cup for something in the hundred gallon range. Which means a gallon of house hold bleach will treat thousands of gallons of water off the top of my head.

If you've got nasty water, some household bleach, and can stomach icky tasting water, your good to go as far as I know.
A call your baloney and raise you pastrami.
Laundry bleach has 1/4 to 1/2 the concentration of "liquid chlorine" used for swimming pools. On an 8m3 pool (that type you assemble) I use 1 liter a day. Chlorine comes in 4-liter bottles and i ususally have two or three. A "permanent" pool has at least triple that ammount of water.
I cannot belive that most people regularly have that much household bleach.

For small-time (up to 100 litres) bleach is OK.
#49
Old 04-23-2009, 07:47 AM
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Quote:
Originally Posted by Ají de Gallina View Post
I cannot belive that most people regularly have that much household bleach.
We're talking about the pool owner. I have 12-20 gallons of Clorox around at any time (I use 2 gallons to shock the pool).
#50
Old 04-23-2009, 08:15 AM
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Watch the pool get hurt, pool!
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