How deep will my well be?

Nobody can tell you the exact depth of a well that hasn't been drilled yet — not us, not the driller, not the state. What you can do is look at every well already drilled near your property. That's a matter of public record: when a licensed contractor finishes a well, most states require a construction report with the location, total depth, water level and yield.

WellsMap indexes 14.7 million of those reports. When you drop a pin, we pull the nearby wells and compute three numbers:

• p10 — the optimistic case. One in ten nearby wells hit water shallower than this.
• Expected depth — a distance-weighted median of the closest wells.
• p90 — the budget case. Nine in ten nearby wells were finished by this depth. This is the number your contingency budget should use.

Why neighbors' wells predict yours

Groundwater lives in layers — sand and gravel aquifers, fractured rock, confined artesian zones. Those layers don't stop at your property line. If forty wells within two miles of you bottom out between 180 and 320 feet, yours is very unlikely to be 60 feet or 900 feet. Geology has local texture, which is why we weight closer wells more heavily and widen the search radius only when data is thin.

What moves the number

• Terrain. Hilltops usually need deeper wells than valley floors; the water table roughly follows the landscape but flattened.
• Rock type. Sandy coastal plains often produce shallow, generous wells. Piedmont granite and gneiss mean drilling until you intersect enough water-bearing fractures.
• Season and drought move static water levels, which affects pump setting more than drilled depth.
• Use. Irrigation and farm wells are often drilled deeper on purpose for storage.

A worked example

In the North Carolina piedmont around Franklin and Wake counties, typical residential wells run roughly 100–400 feet with big local swings — one road can average 150 feet while the next ridge over averages 350. That spread is exactly why a p10–p90 band beats a single guess, and why a fixed-price quote without local data has a fat risk premium baked in.

What to do with it

1. Get the band for your actual parcel with the estimate tool — it's free and uses only public records.
2. Ask bidding drillers to price the expected depth, with a clearly stated per-foot rate for footage beyond it.
3. Budget to p90. If the drill stops shallower, you keep the difference.

A well estimate is a statistical read of nearby drilling records, not a geological survey of your lot. Fractured-rock geology can surprise in both directions — that's precisely what the contingency band is for.