This is a tip EVERYONE should know and I still do this! I use a half filled bottle of water, a small rock, and mark safe/not safe so anyone who's not me knows w

This is a tip EVERYONE should know and I still do this! I use a half filled bottle of water, a small rock, and mark safe/not safe so anyone who's not me knows which way it should be. Pretty sure it was my great-grandpa who taught me that.