Septic companies in Spokane Valley, WA

What the ground in Spokane Valley is like

The USDA soil survey rates mapped ground in Spokane Valley for septic drain-field suitability across roughly 38 square miles. About 100% of the rated ground is classed "Very limited", the survey records severe restrictions for a conventional drain field across most of that ground.

In Spokane Valley, the leading limit is seepage in the bottom layer: water moves through the soil too quickly. That is the opposite of a slow-drainage problem. The risk is untreated effluent reaching groundwater before the soil can clean it, not backup at the surface. The survey flags that limit on about 98% of the rated ground here.

The limiting features the survey records most often here:

• Seepage, bottom layer97.9%
• Filtering capacity14.0%
• Slope10.5%
• Slow water movement7.3%

This is survey data for mapped areas, not a substitute for a site evaluation on your own lot. Conditions on a single parcel can differ from the map.

USDA NRCS SSURGO, ENG Septic Tank Absorption Fields · 99.5% Very limited · Seepage, bottom layer · 64 map units · 37.72 sq mi · read 2026-08-30