I read in First In[/U] about the use of powdered bleach for water purification and whatever else bleach can be used for. Liquid bleach has a shelf life of about six months, correct? Does the powdered bleach have the same shelf life, or is it full strength indefinitely or until it is added to a mixture? It seems powdered bleach could be the answer to the problem of perishable liquid bleach (if this is a problem).