I was just listening to a man on late night radio saying one thing that lots of preppers don't have which they should have is a backflow preventer (plumbing device) for their homes. Without one, if the power was out for an extended amount of time, you might turn on your water only to get sludge from your neighbors. Maybe you wouldn't even have to turn on the water- maybe it would just come leaking out of the pipes- I wasn't sure about this part. Nonetheless, this backflow event could present a toxic situation for you.
I do remember hearing in a presentation years ago (I was in the construction industry at the time) that if, for instance, you were in the same neighborhood where firefighters were battling a blaze, their demand for water pressure could create a backflow situation. Without a backflow preventer, you could turn on the shower (not even knowing there was a fire in your area) and have sewer water come out. Yikes!
Backflow preventers are not too expensive- the man on the radio made it sound like perhaps $200-300 installed would be a reasonable price for one for a typical home. The host of the show said he got a deal with a plumber (maybe he was already having other work done or something like that) and got one installed for just $75.
Does anyone here have a backflow preventer or know anything about this subject?