The reason vinegar works is because most of the blockage (if not in silty areas) is because of mineral deposits in the filter, which is even worse when allowed to dry out...just like on your shower head. Those things build up but because the pores are so small on the Sawyer (and any filter like it) it takes a minuscule amount of mineral deposits to affect performance. This is science and shouldn't require a warning on the label from Sawyer... just a bit of common sense and logic