Bleach shelf life guidelines

[steveinaz]

Being a little bored this morning, I finally decided to research this myself:

If stored between 50-70 degrees: 6 months from manufacture for full advertised strength. It will still be useable up to 1 yr, but at (likely) reduced strength.

If stored above 70 degrees: 3-5 months.

[waterbear]

and the problem is that you never know how long it is stored in a warehouse!

[kelemvor]

Bleach needs Budweiser style born on dates...

[AnnaK]

I sometimes have liquid chlorine, the pool store stuff in carboys, left over at the end of a season. I store it in the garage over winter and then use it after the pool has thawed, just to dump in a dose to make life tough for what algae might want to get going. At this point it really doesn't matter what the strength is anymore because I'm not yet testing or balancing. Whenever I buy a refill I do test the concentration of it. It's sold as 14% but my testing usually puts it at 11%. Good info to have.

[chem geek]

Steve, where did you get that data? The process of degradation is continuous, not something that happens all of a sudden. A good guideline is the half-life chart that is a function of concentration and temperature at the bottom of the Odyssey Manufacturing bulk product page. You can see that 6% bleach, which would be close to the 5% line in their table, lasts quite a long time, while 12.5% chlorinating liquid, which would be in between the 10% and 15% lines in their table, decomposes roughly 3-5 times faster. This tool is interesting, but unfortunately only shows 7 days of decomposition data.

[steveinaz]

Richard, Some of the data came from Clorox's FAQ section. They mentioned that the bleach is actually formulated at higher than advertised strength, so that as it "ages" it should (if stored properly) be at it's advertised strength up to 6 months. It also mentions something about making stronger formulations in the summer months than they do in the winter months to counter-act high summer temp degradation.

I'm not posting with any intention of being an "expert" just passing on some info. I thought the shelf life was like 30 days....

[steveinaz]

Richard,
Does it seem feasable that Bleach would last 6 months, properly stored? What would you think would be max storage time?

[Vtattebury]

Hi folks--

Along these lines, I decided to do a test of "Home Basics" bleach (sold at a ridiculous $1.45/gal.) from my local NJ PathMark store. I know the brand has been discussed before, and the price (and lack of chemical labeling) led me to test it. This is also the FIRST time I've used my k2006 kit, which finally arrived.

So we've got two unknowns here: the percent chlorine, and my ineptitude of testing ;-)

I followed some other guidelines to make a 1/10000 solution (see below)

Following the steps listed below, I poured 100 ml of distilled water, and added 1 ml of the bleach. Then I took 1ml of THAT mixture and added it to another fresh 100 ml of water. *(giving me 1/10,000?)

Using my test kit, I believe I came up with 4.4 parts per million, and the instructions below tell me that's 4.4%. Is my math and process correct? *I compared that with Clorox and came up with 7.8ppm (7.8%?), so I figure I'm not too far off the mark.

If it is indeed only 4.4%, it's probably not worth the price per chlorination.

I followed these steps to make my dilution:
Measure 100mls of water and place in a cup.*
Using your 1ml syringe, remove 1 ml of water*
Add 1ml of your 10% Bleach solution and mix well.*
This is your first 1:100 dilution*

To another cup, add 100mls of water.*
Using your 1ml syringe, remove 1 ml of water*
Add 1ml of your 1:100 dilution solution from the above step and mix well.*
You now have your 1:10,000 dilution needed for your test