there is a thousand year supply of water there, it falls from the sky.
Thank god it isn’t the desert, we will have more water than we know what to do with.
Once you understand that, you'll want to organize an early warning network. Assuming your cell phones are not working, there are commercial radios that are quite handy, depending on the distance and line of sight. When we used to go into certain neighborhoods in Baghdad, there would be early warning networks run by kids. They'd radio or text each other. Some places would use air horns or smoke. Another would even release a big flock of pidgeons from a certain rooftop. Doesn't really matter, so long as you have a way to warn the neighborhood that outsiders are poking around.
More than anything, I'd avoid the temptation to make your house and family a lone fortress. Looters will dissolve in the face of organized resistance. I can't stress that enough. A common defense between 5 families is 10x stronger than 5 lone families.