Is it safe to purify water before storing it in Mylar bags?

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I got some Mylar bags/boxes to store 5 gal water. If I purify with bleach by adding drops of bleach to each bag will the bleach react with the Mylar making it toxic?


First of all, Mylar bags are not the best way to store water. Second, you could just put water into a 5-gallon bucket and put the lid on.

Third, if you live in the U.S., your water already has chlorine in it. Just fill up any food grade bottles or containers you have and you're good to go.

If you want more information about storing water, read

And if you ever need to purify water, read how to do it here:

Comments for Is it safe to purify water before storing it in Mylar bags?

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Do you need to purify well water?
by: Dee

When storing well water for long time storage, do I need to treat the water before storing it?


No, but you might have to purify it at the time you use it. It depends on the purity of the well water. Does it have any chlorine in it at all? Any pathogens? Have you tested it to see what it does have in it?

Please tell us why mylar bags are not good for storing water
by: Ron

Please tell us why mylar bags are not good for storing water.

Why would you want to store water in Mylar bags?
by: Joan

There is nothing wrong with storing water in Mylar bags. They are safe and probably very clean.

But why would you want to? I can imagine the difficulty of putting the bag in something (a box maybe) to hold it upright. Then making sure the edges are completely dry so they will seal. Then trying to seal the opening without spilling the water.

Sorry, just seems like too much trouble to me. I just fill food-grade bottles or bigger water containers and done.

Mylar Water Storage....a great plan!
by: thirsty

mylar bags for water storage:

Water from municipal supplies do not need additional treatment for longterm storage. City treated water well exceeds sanitation needs.

And do not fear a couple of drops of clorine if you are concered about the area between the treatment facility and your tap. (My water runs through 70 year old pipes)

Well water MUST be treated for longterm storage.

Yes, mylar can handle the chemicals in treated water. Straight clorine can be stored in mylar for shorter periods of time.

The good

1. When not in use, mylar bags occupy very little space. 1 five gallon bag with spout can be fit into most any coat pocket. And yes, they are reusable.

( "Boxed water storage kits", include broken-down support boxes, which occupy minimal space and are easy to put together. ) great for those with little storage space.

2. Heavy gauge mylar liquid storage bags (most, if not all, on the market are heavy gauge) block 99+% UV rays and outgas less than most food grade water/food plastic storage containers. Similarly, mylar blocks microscopic bacteria, viruses, & various gasses etc. from passing through & entering the stored water.

3. if NOT overfilled, it is hard to "pop" these bags. (A 5 gallon storage bag is designed to hold 6 gallons) if you fill to 6 gallons and drop or step on the bag it will likely break. 5 gallons, allow you to step in the bag displacing the water under foot without popping the bag.

The bad:

1. Though heavy duty, they are still a plastic bag and therefore puncturable & easier to melt. Consideration to keeping them from sharp objects & DIRECT heat (ash, candles, cigarettes) is imperative. Please note; heavy gauge mylar can take ALOT of heat.

2. If using a boxed water storage kit (a setup including a mylar liquid storage bag to be fitted into a box that adds rigidness to support & transport the bag), know the boxes provided are UNTREATED cardboard. The CANNOT get wet.

Hope this offers some helpful info.


by: Debra

Well it seems to me that in a 55 gallon barrel a mylar liner is a good idea. Since all plastic PETE grade, Food grade etc can leach over time depending on temperature etc. The open top barrel with a mylar liner are very easy to install. The top of the mylar liner is open. I like the open top barrels that you can look in a see what is going on. We have well water that is very clean, however a few drops of clorine or Clorox may inhibit bacteria growth to some extent. I plan on adding stabilized oxygen from time to time and will probably boil and refilter the water if I need to use it. Just my thoughts.

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