To keep the plumber from your doorstep, Roberts strongly advises people to disconnect hoses from their outside taps and make sure the outside taps are shut off. Hoses should also be disconnected from frost-free outdoor faucets, he said. Isolation valves for backyard piping or irrigation should be shut off inside the house. The B.C. plumbing code says a water main should be 18 inches underground in our climate, said Roberts, but in some cases in older homes, or if someone ran their own irrigation line underground, it may be shallower and could freeze.