bleach shelf life


Well-known member
May 22, 2010
Dexter, MI
Pool store has a good deal on 12.5% "bleach", 10.99 for 4 gallons. I would like to stock up but do not know how long it will keep before it is say 10%. Apparently they usually only stock 10% but couldn't get it so got 12.5% and are selling it for the same price. They only have a few cases left and I already bought 4 cases. I will be storing it in a cool dark enviroment. What do you think?


LifeTime Supporter
Nov 18, 2009
Sacramento, CA
From an old thread...

chem geek said:
...The table at the end of this link shows how the half-life (the time it takes to lose half of its concentration) of 20% chlorine even at 75F is 70 days. The fastest loss occurs during the earlier part of that time period. A loss of 10% of the concentration, going from 20% to 18%, happens after just 10 days and that's assuming 75F temperature....


TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
12.5% should be fine for the rest of the season if it is keep reasonably cool. It will lose a little strength by the fall, but not enough to worry about.

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