The king of clean has to be the bottle of bleach. Pretty much nothing survives a bleach cleaning (other than that clean bleach smell). And by cleaning, I mean disinfect. But if you like to use bleach sparingly, then you need to get into the habit of writing the date you bought it. Come to find out, bleach has a shelf life and begins to degrade after six months. It will still be effective at disinfecting until a year has passed. As it breaks down, it turns into water, salt and oxygen and therefore not be effective for sanitizing whatever you'd like to sanitize. One of the surefire ways to know if your bleach is expired is if you open the bottle and you don't smell any kind of bleach odor. f you open up a bottle and it still has a potent bleach smell, then it's likely that it will still disinfect. So writing the date you purchased it will give you a good timeline of its effectiveness. You can also decipher the manufacturer’s code. On Clorox, look for the two-lined code above the label. Use the third and fourth numbers to determine the last two numbers of the year it was manufactured. After those two numbers will be three number indicating the day it was manufactured (numbers go from 001 to 365 indicting the day of the year it was made). In the meantime, store your bleach at room temperature (around 70°F), out of sunlight and in its undiluted form (not mixed with water).