Methodology & sources

Every number on this site is computed from public records. This page shows the work.

Source data

All well records come from the well construction report database at the Washington State Department of Ecology — the state's official repository of well reports, where Washington drillers are required to file completion reports. We refresh our copy weekly from Ecology's public data service (342,388 water well records at last refresh, 2026-06-11). Each well in our reports links back to its original Ecology record, including the scanned driller's report.

Filters

• Water wells only — Ecology's database also contains soil borings, environmental borings, dewatering and resource-protection wells, and decommissioning reports, all excluded from statistics. Legacy records with no project type (mostly pre-1996 well logs, which carry depths, water levels, and yields) are included as water wells
• Depth statistics use recorded total depths between 0 and 5,000 ft (sanity bound); the source's -1/0 "not recorded" sentinels are treated as missing
• Static water level statistics use measurements 0–2,000 ft below ground surface; a recorded level of exactly 0 is treated as missing (it is the source's default), which slightly under-counts flowing artesian wells
• Yield statistics combine the current database's flow-rate field with pump-test yields from Ecology's legacy well-log database (matched by well report ID), 0–5,000 gpm
• Records with no county assigned (~2,500 statewide) are excluded from county pages
• Counties with fewer than 10 records are not published

Statistics

We report medians and interquartile ranges (25th–75th percentile) rather than averages, because well data is heavily skewed — a few very deep wells would distort an average. "Recent" figures cover wells completed since 2016. Driller tables count wells by the driller on logs filed since 2016 — Washington's bulk data records the driller's license number, which we map to the licensed individual's name using Ecology's licensed-driller roster.

Cost estimates

We do not collect quotes. Cost ranges apply published national per-foot rates to the local median depth — the local depth is what makes the estimate useful, and it comes from actual drilled wells nearby:

• Drilling + casing: $25–$65 per foot
• Complete system (pump, pressure tank, hookup): $60–$100 per foot

Rate sources (last checked 2026-06-11):

• HomeGuide — Well Drilling Cost (2026) — $25–65/ft drilling + casing; complete systems $3,000–15,000, most $5,500–9,000
• Angi — How Much Does Well Drilling Cost? (2026) — cross-check: drilling alone $15–25/ft; complete installation $25–65/ft
• The Well Guide — Well Drilling Cost (2026) — depth tables (e.g. 150 ft: $9,000–13,000 all-in); Mountain West/Pacific NW: $35–65/ft, systems $10,000–25,000
• Washington State Department of Ecology well construction reports — all depth/static-water-level/yield figures are computed from Ecology records, not estimated

Estimates are planning figures, not quotes. Site access, geology, casing depth, and water treatment needs move real prices substantially.

Known data limitations

• Location accuracy: Ecology plots wells at quarter-quarter-section centroids — roughly a ±0.5 mile square, per Ecology publication 24-11-027. Records missing quarter-quarter data plot at quarter-section or section centroids (coarser). Distances in our reports inherit this precision.
• Street addresses are recorded on about 87% of reports and assessor parcel numbers on about 42%; both are driller-entered and unstandardized.
• Not every well is registered — older and hand-dug wells are under-represented.
• Some records contain filing errors; we propagate the official record as filed.

Corrections

If a number here looks wrong, email us (or reply to any report). Confirmed errors are corrected and logged on the changelog. In this niche one wrong number costs more trust than ten missing features — we'd rather show less and be right.

About

Washington Well Data is an independent data publisher. We are not affiliated with Ecology, the State of Washington, or any drilling company. Revenue comes from property reports and from connecting homeowners with licensed local drillers — never from selling rankings or placements in the statistics.