Septic and the aquifer
Spokane draws its drinking water from the Spokane Valley–Rathdrum Prairie Aquifer, which the EPA designated a sole source aquifer in 1978 and which supplies water to more than 500,000 people in the region. That makes septic system care in the Spokane area more than a private matter. Wastewater that isn't treated properly can reach groundwater, and the aquifer's coarse sand and gravel let water move quickly. Many homes in the city are on sewer, but rural and suburban properties in Spokane County may rely on septic systems. Pumping on schedule, avoiding harsh chemicals and medicines down the drain, and keeping the drain field healthy protect everyone's water.
Frost and freezing 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. NOAA's engineering weather data for Spokane records about 72 freeze-thaw cycles a year. Septic tanks and lines can freeze when they're shallow, when snow cover over them is compacted, when the house is vacant, or when a leaking fixture sends a trickle that freezes. Leave snow undisturbed over the system, keep vehicles off it, fix leaks, and talk to a contractor about precautions if the house will be empty in winter.
Snowmelt and spring
NOAA's data lists a 50-year ground snow load of 42 pounds per square foot for Spokane, and that snow melts in spring. Snowmelt and spring rain can saturate soil over the drain field. Reduce water use during melt, direct downspouts away from the field and watch for soggy ground or odors.
Wells
Some rural Spokane County homes have private wells as well as septic systems. Test your well water regularly, and keep proper separation between the well and the drain field.
Permits and records
Septic repairs and new systems in Spokane County require a permit from the regional health district. Keep records of pumping and repairs, which are also useful when you sell.
Before you hire
Ask Spokane-area septic contractors whether they'll pump through the main access and inspect baffles and filters, how they handle frozen lines, whether they evaluate the drain field, and who handles permits. Use L&I's contractor lookup to check their Washington registration, bond and insurance.
Signs of trouble
After snowmelt, walk the area over the tank and drain field. Soggy patches, odors, slow drains and gurgling toilets mean the system is struggling. Catching problems in spring gives you time to repair before heavy summer use.
Risers and access
Buried tank lids under snow are hard to find in winter. Risers that bring the lids to the surface, insulated in cold climates, make service faster and let a contractor reach the tank in an emergency.