Here is the People's Repuplik of Kalifornia there is a simple way to bring up the concept of prepping.

As we are subject to at least weekly small earthquakes and the radio and television carry ads from FEMA or some other sort of agency to "..make a kit, make a plan," it becomes easy to drop the concept into conversation. It gets very easy when we have any sort of quake of significance that gets everyone's attention.

I would NEVER disclose the true extent of our preps, however I often let folks know that I listened to the ads and we keep a case of water and a few days worth of ready to eat canned goods in case the "big one" smacks us. Then you listen to what people say and can begin to build a prepping relationship----all while still keeping OPSEC. You do not immediately let someone know the full extent of what you have, where it is kept, etc!