If you need it buy it. It should be ok to at least get you through a good part of the swim season. just keep it in the house and tightly sealed. I have a vacuum sealing machine and I seal up my extra DPD powder and titrant in vacuum sealed bags for storage. I just opened a 4 year old DPD power that was vacuum sealed and the color is still light grey and it is not clumped. As I said about the titirant, if it is peach or pink color throw it out. I like to replace it yearly because if it has started to go bad it will read lower than the actual chlorine level (in other words, you will need more drops) However, it's not that big a deal if the chlorine is a bit higher than you think. It would be more of a problem if the chlorine was lower than you think.