Water - Treat before freezing?

Short form question:

Should I treat water with chlorine or iodine prior to freezing for long term emergency storage? I've bought gallon bottles of water in PET containers with handles. I was planning on opening the bottles and pouring out a small amount to allow room for freezing, but I'm not sure if I should also chemically treat beforehand for long-term storage.

Long form:
In a step that guarantees I'll be reminded how old I'm getting, as this is the sort of thing my parents used to do, I've just converted an old refrigerator in the garage to a wine cellar. Using a commercial thermostat intended for the purpose, the upper box is now temp controlled at ~55 degrees F. The unit basically cycles the fridge/freezer power on/off to regulate the temperature in the fridge box.

Unfortunately, good wine temps means that the freezer portion usually hovers around 20-24 degrees F. This is cold enough to freeze, but not cold enough that I consider it "safe" for frozen food storage, especially since the temperature cycles up and down as the wine thermostat does its thing. (And its obviously too cold for beer storage!)

I figure I could create a win-win-win situation by using the freezer as additional emergency water storage. Having six or so gallons of frozen water in the freezer box will also add thermal mass and smooth out the thermal cycling as the thermostat does its thing, which is better for the wine, and lastly it means I'll have a bunch of extra ice on hand should I need to transfer that to my real frozen food storage areas in case of extended power loss.

Given that I'm using commercially bottled water, should I even bother? As it happens the water that came in the containers I prefer is that "filtered" product, meaning its basically treated tap water, not spring water. But I will need to OPEN the containers to make room for freezing, thus introducing a possible contamination point.

Also, everything I've read says that halogen treatments such as chlorine and iodine don't work well at low temperatures. I guess I would treat at room temperature for the recommended time, then freeze, but still not sure if its (A)worth it, and (B)potentially giving me false security.

Opinions?

Thanks much.

I have no idea, sorry. But this an interesting concept, I can't wait to see what we learn about this method of water storage. My gut instinct is to just freeze it as is, but what do I know...

I did this when I was at my folks, but using OJ containers and well water that needs to treated before you drink it anyway. Not sure I'd trust PET with freezing- it usually isn't very robust.

Since it's commercial drinking water, I don't see any reason to treat it before freezing.

It's probably been through a reverse osmosis process. And it's likely to have been ozonated to knock off any stragglers like algae.

Anyway, if there are microorganisms left over, they will be in stasis as long as the water is frozen.

As long as you leave expansion room there should be no problem. Leave some room & go back after the rest of the jug has frozen & top it off with tap water.

As far as additional treatment goes I wouldn't worry about it since it's going to be frozen. If you were going to set the jugs in a closet they would need treatment even using tap water. Municipal supplies here in the States are supposed to have a residual amount of chlorine at the tap farthest from the treatment plant. My water relatively reeks of chlorine. This breaks down over time.

My opinion is that if you're concerned about any chance of contamination, it would make the most sense to treat the water after you've thawed the ice and are ready to drink it. In other words, treat it close to the time of use, rather than up front. Even just adding some bleach should be fine.

It probably doesn't make that much difference either way, if you're careful about handling and storage, but in case something goes wrong that you're not aware of, it's logical that it's better to treat close to when you use it to be safest. Actually, I can't really think of any advantage to treat up front, unless you know for sure that the water source is of questionable quality, then I would consider it. As long as you treat at time of use, any accidental contamination of already clean water during the initial handling will be taken care of. I would consider pre-treatment up front if I knew the water quality was questionable because I will have the time and resources to properly treat it then and I might not have that luxury if I needed to heavily treat water during the emergency.

This reasoning may sound contradictory to what I said, but it's more a matter of risk management that dictates what to do. Like I said, if you're starting with clean water, the risk is very low even if you don't treat at all, but if you already know the water is questionable to start with, the risk is high. Say I wanted to hand out a frozen jug or two of questionable water to a neighbor to take home during some emergency. Maybe they said they have bleach but it turns out that they don't and can't boil that questionable water effectively, then they're definitely at risk from getting sick. Or maybe I grab a frozen jug before heading out for supplies or something during some emergency and I forget to bring a filter or tablets along. I sure would've wished that I had treated the water up front since I alredy knew the water was questionable. Would I risk drinking that jug on the road? I probably wouldn't.

Anyway, just my overthinking ramblings.

Before you freeze the commercial jugs of unopened water do an experiment. Get an identical empty jug from somewhere, fill and freeze it. See if the sides bust out or the top comes off. Make sure you place the jug in a baking pan just in case of failure.

Reason: I had friend that froze his milk and never had a problem. We also thermal-massed our chest freezer with water in the same manner incident-free. Give it a whirl.

Two cents....

I'd think not.

BTW, I've always heard that 58 was the appropriate temp for a cellar. It's what I keep mine at, and my dad keeps his wine shed (yes, a whole shed ... making it is his hobby).

Alameda County is where Oakland, California is. Here's their page on how to store water long-term while we wait for the next big quake:

http://www.acwd.org/faq.php5?category_id=57

It covers tap water and store-bought bottled water, how to treat, how long to store (in liquid state). I note that they don't expect the water to be frozen and suggest filling to the brim, leaving as little air in the container as possible.

I've had questions about some of their suggestions and have emailed them (their contact link is at the top of the page) with my questions and gotten thoughtful, real answers from guys who seem to know what they're doing.

I freeze water in containers for camping at Burning Man. I use the containers as ice for the ice chest, then drink it after it melts. Not filling the container full is a good idea, but it doesn't always prevent containers from cracking. Water expands in all directions as it freezes, not just up (where the air space is). I haven't had a lot of containers crack, but over the years I've had a few leak from breakage. Maybe from ice expansion, maybe from brittleness of the container. I freeze these containers with tap water the week before we leave, and all are consumed by the end of the following week, so long-term issues don't apply to my use.

In addition to not filling the bottles all the way, try placing the bottles on an angle when freezing. We freeze samples all the time in the lab and always place the container on a slant. To date we have not had any containers break when we use this method. In the past we have had containers break when simply frozen in the upright position.

Pete

paramedicpete's right: place the bottles at an angle in the freezer. It really works.

I was thinking about Pete's post this morning and why it works but it's a complete mystery to me. What the heck is going on when it's slanted that is different from a level container? Egads, did I miss the MythBuster's episode on this???

Slanted allows more room for expansion as the water turns to ice.

(Darn it, wildman beat me to it. Anyway, my long-winded version follows.)

From what I've observed:

When water freezes, it starts by forming a crust at the top with liquid water underneath. I assume this is because ice crystals are less dense, so they float to the top.

In a container, this ice crust forms an effective pressure seal once it reaches a certain thickness. When the rest of the water slowly freezes (and expands) it exerts equal force against the "ice crust" and the rest of the container wall.

For a container oriented vertically, the surface area of the ice crust will be smaller and thicker for a given volume of water. So, the container wall gets the maximum pressure possible -- and may burst.

For a container oriented at an angle (horizontally) the surface area of the ice is the largest possible, and so is thinner and weaker. It is likely more pliable for a longer period, so it may move and bow before it becomes an absolute pressure seal. So, there is less pressure on the container wall, and less chance of failure.

(I warned you, long-winded. Feel free to "flame" my ice theory. It's possible that I am hopelessly snowbound on this.)

I don't believe that it is necessarily tied to ice crystal density as it is temperature conduction. The surface loses its heat quicker, hence ice. The mass (volume) as a whole takes longer to have the cold penetrate (heat loss) at the center.

Anyone?

(Caution! Nerdy and increasingly OT discussion in progress!)

I'll buy that. Air cools more quickly than water. That would certainly apply to an open container, but would likely apply to a closed container as well, as long as there was an air space at the top.

I can attest to the "pressure seal" effect. When my polyethylene rain barrels start to freeze over in a serious way (2" of ice) I break the ice with a spade or axe and the water squirts upward quite impressively. I suppose some sort of foam "tube" (like the ones you wrap water pipes with) would keep a hard seal from forming. Gotta try that.

I've seen a picture where it was at just the right temperature & pressure that it froze into a spike. It happens occasionally with ice trays but this was the first time I'd seen it happen on a large scale.

Water hates compression. That is why depth charges work so well.