Long winters, real freeze risk
Spokane winters are cold and snowy, with about 72 freeze-thaw cycles in an average year according to NOAA's engineering weather data. Pipes in exterior walls, crawlspaces, garages and outbuildings need protection, and outdoor spigots and irrigation systems must be shut down properly every fall. The cost of insulation and a fall checklist is small compared with water damage from a burst pipe.
Backflow testing is required
The City of Spokane requires homes with an irrigation or sprinkler system to have a backflow assembly, and that assembly must be tested every year, ideally before the irrigation is turned on in spring. Even an unused system needs its annual test. Testing must be done by a qualified tester; ask the plumber or irrigation company whether they perform the test and file the results with the city, or whether you need to arrange it separately. Backflow assemblies are also vulnerable to freezing, so drain or insulate them according to the manufacturer's instructions before winter.
Frost depth for buried lines
A joint City of Spokane and Spokane County codes policy sets frost depth at 24 inches below finished grade unless a soils investigation supports a different depth. Water service lines, irrigation mains and lines to detached buildings need to be buried deep enough, or insulated well enough, to stay out of the frost. Ask how a new line will be protected where it rises above ground.
Protecting the aquifer
Spokane's drinking water comes from the Spokane Valley–Rathdrum Prairie Aquifer, which the EPA designated a sole source aquifer. That makes proper disposal of drain cleaners, solvents and other chemicals important. Don't pour them on the ground or into storm drains. If you're on a private well outside city limits, ask a plumber about well testing and backflow protection for any irrigation connected to the well.
Snow and roof drains
Heavy snow and ice can block roof drains and downspouts, sending meltwater against the foundation. If your basement or crawlspace takes on water in late winter, check that downspouts discharge well away from the house and consider a sump pump if water collects regularly.
When a pipe freezes
Close the main water valve if you see any sign of a split, open the affected faucet, and warm the pipe gently with a hair dryer or space heater kept at a safe distance. Never use an open flame. If you can't find the frozen section or water is leaking, call a plumber.
Before you hire
Ask Spokane plumbers whether they handle annual backflow testing, how they protect new lines from freezing, and whether the work needs a permit.