Drilled Well vs Dug or Bored Well: Depth, Safety and Cost
EPA describes three kinds of private wells. Dug and bored wells are wide holes, roughly 10 to 30 feet deep, lined with stone, brick or tile and not cased continuously. Drilled wells are made by rotary or percussion rigs, can run thousands of feet deep, and use continuous casing, which EPA says gives them a lower risk of contamination.
Nearly all new household wells are drilled. Our well drilling cost calculator prices them at $25–$65 per foot (HomeAdvisor, 2026), so a 150-ft well with a pump and pressure tank comes to about $5,250–$14,250. Dug and bored wells still serve many older farmsteads, which is why owners weigh repairing one against drilling a replacement.
At a glance
| Drilled well | Dug or bored well | |
|---|---|---|
| How it's built | Rotary or percussion drilling rig | Dug by shovel or backhoe, or excavated with a bucket auger |
| Typical depth (EPA) | Can be thousands of feet; most household wells are far shallower | About 10 to 30 feet |
| Casing | Continuous steel or plastic casing, grouted near the surface | Stone, brick, tile or concrete lining, not continuous |
| Contamination risk | Lower, per EPA, because of depth and continuous casing | Higher; draws shallow groundwater that surface water reaches easily |
| Drought | Reaches deeper water that holds up better in dry spells | Shallow water table can drop below the well |
| Usual pump (EPA) | Submersible pump inside the casing | Jet pump above ground for depths of about 25 ft or less |
| New-well cost | $25–$65 per foot plus pump, tank and permit (our calculator) | Rarely built new; quotes are local and many owners replace rather than rebuild |
Safety: why depth and casing matter
A dug well's lining has joints the whole way down, and it draws from water just below the surface. Rain, runoff and anything spilled nearby can reach it quickly, which is why shallow wells are the ones most often hit by bacteria after storms and floods.
A drilled well seals out shallow water with a continuous casing and grout. State rules set the minimums: Tennessee, for example, requires the water source at least 19 feet below the surface and watertight casing from at least 19 feet down to 6 inches above grade (Tenn. Comp. R. & Regs. 0400-45-09-.10).
Cost: drilling new vs keeping a dug well
Our calculator multiplies depth by published per-foot rates: $25–$40 through sand and gravel, $35–$55 through sedimentary rock and $55–$85 through granite, then adds a permit ($200–$500), an installed pump ($900–$2,500) and a pressure tank ($400–$1,500). At 200 feet in sedimentary rock that comes to $8,500–$15,500.
Keeping a dug well running usually costs less up front, but recurring bacteria problems, low water in droughts and treatment equipment add up. If the well keeps failing tests after disinfection, a drilled replacement is usually the lasting fix.
Pumps and water pressure
EPA notes that jet pumps are the common choice for shallow wells of about 25 feet or less, mounted above ground and pulling water up by suction. Deep drilled wells use submersible pumps inside the casing.
NGWA reports a typical household submersible pump costs $3,000 to $3,200, against about $1,545 to $1,570 for a jet pump, so switching from a dug well to a drilled one usually means a new pump as well as a new hole.
Which one makes sense for you?
Building new, drill: it's the standard for household supply, it's what lenders and inspectors expect, and it's the type state construction rules are written around.
Already on a dug or bored well, test it every year for bacteria and nitrate, keep the cover sealed and the ground sloping away from it, and have a licensed well contractor compare repair and replacement if tests or water levels start slipping.
Frequently Asked Questions
Is a drilled well better than a dug well?
For drinking water, usually yes. EPA notes drilled wells have a lower contamination risk because of their depth and continuous casing, and they hold up better in droughts.
How deep is a dug well?
EPA puts dug and bored wells at roughly 10 to 30 feet deep, with a wide diameter and a lining of stone, brick or tile that isn't continuous.
How much does it cost to replace a dug well with a drilled well?
Our calculator puts a 150-ft drilled well with a pump and pressure tank at about $5,250–$14,250 when geology is unknown. Your driller's local depth and rock type set the real number.
Can I keep using my old dug well for irrigation?
Often, as long as it's properly covered and isn't connected to the house supply. If you abandon it, state rules usually require it to be filled and sealed by a licensed contractor.
Information only — not legal or financial advice. Data last reviewed 2026-10-17.
Sources
- EPA: Learn about private water wells (types of wells)
- HomeAdvisor: Well drilling cost (2026) (third-party estimate)
- Tenn. Comp. R. & Regs. 0400-45-09-.10: Well construction standards (Cornell LII)
- NGWA — Well Owner's Guide (2021, hosted by University of Maryland Extension)
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