I received an interesting question about the shelf life of bleach. There is a rumor circulating out there that once a bottle is open, it loses its effectiveness after a month. Another bleach myth to debunk!
Let's start at the beginning.
Bleach stability is affected primarily by temperature: hotter temperatures accelerate the decomposition of sodium hypochlorite, Clorox’s active ingredient. An open or closed container, does not matter.
This is why we have a Clorox "bleach calendar" that we use to make bleach in our plants. In summer, we add extra hypochlorite to insure that our 6.0% active level is maintained for approximately 6 months at an ambient (70°F) temperature.
Product life cycle information would suggest that from manufacture to store shelf to home is usually around 4-8 weeks. Thus, there is typically 3-5 months for normal home usage still available where the label strength is available.
Let's examine the worst case conditions. Even in very hot conditions, let's say a constant 90°F; the label strength is still available for 3-4 months.
These types of conditions are not likely to occur in homes. While the outside temperature may spike during the day, there is a cycling that typically occurs in the home. This prevents the constant external temperature exposure and means the product temperature may be temporarily affected, but will rise and fall over time. Unless the product is sitting in direct sunlight for an extended period of time, I would speculate that the maximum temperature it will reach is 80°F.
Now let's address the loss of effectiveness. The maintaining 6% active hypochlorite level is a requirement for our disinfecting registration with the EPA. For effective cleaning in the laundry and around the house, we can reduce the active level well below 6% and still provide the standard of excellence consumers expect from Clorox Bleach.
So to recap:
- We add extra bleach during manufacturing to take into account expected temperature changes and to maintain our stated label 6% sodium hypochlorite level for Clorox Regular-Bleach.
- Under most typical home storage conditions this 6% active level will be maintained at least 6 months. Excellent performance should be expected for around a year under these conditions.
- Extreme exposure may reduce the active level below 6%, but excellent performance will be maintained for laundry and home cleaning for at least 9 months.
- Opening the bottle does NOT have an effect on hypochlorite stability nor make the product ineffective.
