They (meaning manufactures. I’ve asked tide, arm and hammer, and oxiclean) say liquid detergent has a one year shelf life. Powder detergents they say as long as no moisture has gotten into the powder it’s fine though. Something about stabilizers in the liquid. I do my fair share of “extreme” couponing however hardly ever use liquid detergent. I do get a fair amount weekly free or cheap liquid detergent (harder to get deals on powder but not impossible) that I gladly give away to friends, family and shelters/vets offices though.

Off topic or on, but for example, I bought a big bag of Sodium Precarb 25lb bag I think . I keep them all in 1 gallon juice jugs. The product offgases - no noticable in small, but the bottles swell. And you know what, I open the bottles to release the air/swelling ...and literally if I check back a couple months later, the bottles are swelled again. Just saying, to some degree, even powered stuff does things if one is observant.

I’ve never experience any swelling in my containers that I keep my powder detergents in. I put them in containers that keep most of the air out. I found some that are for brown sugar and flour and have several of them for my overstock of powder detergent. I keep them in my cellar that’s temp/humidity controlled. May depend on where they are stored too.