Research · updated 2026-08-14 · download the county-level CSV
California Well Depth & Drilling Cost Index
Drilling a private water well in California means paying by the foot — so the two questions every well owner asks are how deep and how much. We computed both for all 58 counties with enough records to be reliable, from 750,016 official DWR well records.
Statewide, the median well reaches 215 ft, and a complete system — drilling, casing, pump, pressure tank, and hookup — typically runs $18,000–$30,000. But the county spread is large:
Deepest counties to drill in California
| County | Median depth | Typical depth range | Complete system |
|---|---|---|---|
| Kern | 400 ft | 260 ft–620 ft | $36,000–$60,000 |
| Madera | 395 ft | 295 ft–566 ft | $36,000–$60,000 |
| Tuolumne | 350 ft | 200 ft–550 ft | $34,800–$58,000 |
| San Luis Obispo | 340 ft | 180 ft–500 ft | $25,200–$42,000 |
| Santa Barbara | 340 ft | 166 ft–547 ft | $34,080–$56,800 |
Most expensive counties to drill in California
| County | Complete system | Drilling & casing only | Median depth |
|---|---|---|---|
| Kern | $36,000–$60,000 | $15,000–$39,000 | 400 ft |
| Madera | $36,000–$60,000 | $15,000–$39,000 | 395 ft |
| Tuolumne | $34,800–$58,000 | $14,500–$37,700 | 350 ft |
| Santa Barbara | $34,080–$56,800 | $14,200–$36,920 | 340 ft |
| Colusa | $32,400–$54,000 | $13,500–$35,100 | 245 ft |
Download the full county table (CSV)
How to read this
- Depth is measured; cost is modeled. Depths are the median of recorded drilled depths per county. Cost applies published California per-foot drilling rates to that local median depth — a planning estimate, not a quote. Actual bids vary with geology, casing, site access, and water depth.
- Counties below 30 records are excluded so a thin sample can't produce a misleading superlative.
- Records are drilling events from the state database, which include some replacement and abandoned wells; deeper counties reflect real local geology (bedrock, aquifer depth).
Sources & methodology
- California well records: DWR (refreshed weekly; see our general methodology).
- Percentiles (p25/median/p75) computed per county; cost from published per-foot rate ranges applied to the local median depth.
The county table is free to use with attribution to California Well Data (californiawelldata.com). For a specific county, a custom cut, or the underlying records, email — usually same-day.
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