I keep a few large bottles of sterile saline solution in the medicine cabinet for all sorts of emergencies. Mostly I use it to rehydrate my soft contact lenses during the day. The disinfecting solution is a little too expensive to use every time my contacts start feeling dry.
The other reason I keep bottles of sterile saline is for irrigation of wounds. My kids are always coming inside with scrapes and scratches, and the first thing I do is saturate the wound with normal saline or saline spray. I'm concerned about using regular tap water when the wounds are deep, because I don't want to introduce all those chemicals into the exposed skin.