ZIP 99110 falls in Stevens County, Washington, where we hold 15,048 parcels measured as septic county-wide and 6,017 on sewer. We do not have a per-ZIP parcel count for this county, so this is the county total, not a count specific to ZIP 99110.
ZCTA 99110 is not entirely inside one county. Land-area share is from the 2020 Census ZCTA-to-county relationship file.
| County | Land in this ZIP | Documents held | On septic (county) | On sewer (county) |
|---|---|---|---|---|
| Stevens County, Washington | 93% | 2,716 | 15,048 | 6,017 |
| Spokane County, Washington | 7% | 27 | 36,413 | 127,463 |
Land-area overlap is from the 2020 Census Bureau ZCTA5-to-county relationship file, not an estimate of ours. Parcel and document counts are rows we hold, not a survey of every property in the ZIP. Last verified 2026-09-01.
We hold 15,048 parcels measured as septic for Stevens County, Washington as a whole, not broken out by ZIP.
ZIP 99110 spans 2 counties: Stevens County, Washington, Spokane County, Washington.