SC By SCWS Team | January 18, 2025 | 10 min read
Deepen Existing Well Cost
Is your well running low or going dry? Deepening an existing well can reach deeper water sources at a fraction of the cost of drilling new. Typical deepening projects cost $5,000-$15,000. This guide covers when deepening makes sense, the process, costs, and how to decide between deepening and drilling a new well.
💲 Quick Cost Summary
- • Mobilization/setup: $1,000 - $2,500
- • Drilling per foot: $40 - $100
- • New casing/screen: $15 - $30/foot
- • Typical 100 ft deepening: $6,000 - $12,000
- • Pump reinstallation: $500 - $1,500
When Does Well Deepening Make Sense?
Deepening isn't always the answer—it depends on your well's condition, local geology, and economics:
Good Candidates for Deepening
✅ Good Casing Condition
Existing casing is sound, no corrosion or damage
✅ Adequate Casing Diameter
6" or larger allows drilling equipment access
✅ Straight Well Bore
No significant deviation that blocks drilling
✅ Water at Greater Depth
Neighbor wells or geology suggest deeper water
✅ Moderate Depth Increase
Need 50-150 additional feet
✅ Ideal Location
Well is well-positioned, don't want to relocate
Poor Candidates for Deepening
❌ Damaged Casing
Corroded, cracked, or collapsed casing
❌ Small Diameter
4" or smaller casing limits options
❌ Crooked Well
Significant deviation blocks drilling
❌ No Deeper Water Expected
Area geology doesn't support deeper aquifers
❌ Very Deep Already
Current well is 400+ feet—new well may be better
❌ Old/Unknown Construction
Don't know well specifications or history
📹 Video Inspection First
Before committing to deepening, a video inspection ($300-$800) is essential. It confirms casing condition, measures actual diameter, checks for obstructions, and verifies the well is straight enough for deepening equipment.
Well Deepening Costs Explained
Cost Breakdown
| Cost Component | Cost Range | Notes |
|---|---|---|
| Mobilization/Setup | $1,000 - $2,500 | Moving drilling rig to site, setup |
| Pump Removal | $200 - $600 | Must pull pump before deepening |
| Drilling (per foot) | $40 - $100 | Varies by geology—rock vs. softer formations |
| Casing (per foot) | $15 - $30 | If extended casing needed |
| Screen (if needed) | $300 - $800 | For unconsolidated formations |
| Grout Seal | $200 - $600 | Sealing new casing section |
| Well Development | $500 - $1,500 | Cleaning and maximizing new production |
| Pump Reinstallation | $500 - $1,500 | Includes additional drop pipe |
Total Cost by Deepening Amount
| Additional Depth | Typical Total Cost | Comparison to New Well |
|---|---|---|
| 50 feet | $5,000 - $8,000 | 25-40% of new well cost |
| 100 feet | $7,000 - $12,000 | 35-50% of new well cost |
| 150 feet | $9,000 - $15,000 | 45-60% of new well cost |
| 200+ feet | $12,000 - $20,000+ | 60-80% of new well cost |
💡 Rule of Thumb
If deepening cost exceeds 50-60% of a new well, seriously consider drilling new instead. You'll get a completely fresh well with full lifespan and no inherited issues from the old well.
The Well Deepening Process
Step 1: Assessment
- Review well records (depth, casing diameter, construction)
- Video inspection to assess casing condition
- Research area geology and neighbor well depths
- Determine target depth for deepening
Step 2: Permitting
- Submit well modification permit to county
- Wait for approval (typically 1-2 weeks)
Step 3: Pump Removal and Preparation
- Pull existing pump, drop pipe, and wire
- Clean out any debris or sediment
- Verify well condition matches expectations
Step 4: Drilling
- Lower smaller drill bit through existing casing
- Drill through bottom of existing well into virgin rock
- Monitor for water-bearing zones
- Continue to target depth or until adequate water found
Step 5: Casing and Completion
- Install smaller-diameter casing in new section (if needed)
- Install screen in water-bearing zones (for unconsolidated formations)
- Grout seal between old and new casing sections
Step 6: Development and Testing
- Develop well to maximize production from new zones
- Conduct yield test to measure improvement
- Test water quality from new depth
Step 7: Pump Installation
- Install pump at new, deeper setting
- Extend drop pipe and wire as needed
- Test system operation
- File completion report with county
Deepening vs. New Well: Making the Decision
| Factor | Favors Deepening | Favors New Well |
|---|---|---|
| Cost | Under 50% of new well | Approaching 60%+ of new well |
| Casing condition | Good, no damage | Corroded or damaged |
| Depth increase needed | 50-150 feet | 200+ feet |
| Location | Current location ideal | Better location available |
| Well age | Relatively young, good construction | Very old, unknown quality |
| Deeper water certainty | Good evidence of water | Uncertain geology |
Risks and Considerations
No Guarantee of Success
Like all drilling, deepening carries risk—you may not find additional water. Responsible contractors:
- Research area geology thoroughly before recommending deepening
- Review neighboring well logs for evidence of deeper water
- Discuss realistic expectations and alternatives
- Explain their policy if water isn't found
Water Quality Changes
Deeper water may have different characteristics:
- Higher or lower mineral content
- Different hardness levels
- Potential for sulfur or iron
- Temperature changes
Always test water quality after deepening to identify any treatment needs.
Pump Considerations
Deeper settings affect pump requirements:
- Higher head: Pump must lift water greater distance
- More horsepower: May need larger pump motor
- Additional drop pipe: More pipe and wire needed
- Operating costs: Slightly higher electricity use
Alternatives to Deepening
Before committing to deepening, consider these alternatives:
🔧 Alternative Solutions
Hydrofracturing
$3,000-$10,000 — Opens new fractures without drilling deeper
Well Rehabilitation
$2,000-$8,000 — Clears blockages that may be limiting yield
Storage Tank System
$3,000-$8,000 — Stores water during off-peak times
Water Conservation
Reduce demand through efficient fixtures and practices
If your well runs out daily but refills overnight, a storage tank may solve your problem without any drilling. Learn more about options if your well runs out of water daily.
Frequently Asked Questions
How much does it cost to deepen an existing well?
Deepening costs $5,000-$15,000 depending on depth added and geology. Drilling runs $40-$100/foot plus mobilization, casing, and pump work. Adding 50-100 feet is most common.
Can any well be deepened?
No. Requirements include: good casing condition, adequate diameter (6"+), straight bore, and reasonable expectation of deeper water. Video inspection determines feasibility.
When should I deepen vs. drill new?
Deepen when casing is good, cost is under 50% of new well, moderate depth increase (50-150 ft) is needed, and there's evidence of deeper water. Drill new when casing is damaged, well is crooked, or much deeper is needed.
What if deepening doesn't find more water?
There's no guarantee. Good contractors research geology first and discuss expectations. You'll typically owe for drilling performed even if water isn't found. Discuss the policy before work begins.
How much deeper can a well be drilled?
Technically 50-200+ feet, limited by casing diameter, condition, and economics. Most projects add 50-150 feet. Beyond that, new wells often make more sense.
Does deepening require a new pump?
Usually the existing pump works if in good condition—just needs deeper setting with extended drop pipe. Old or undersized pumps may need replacement. Deeper settings may require higher horsepower.
How long does well deepening take?
Most projects take 2-4 days: pump removal, drilling, casing/screen installation, development, and pump reinstallation. Add 1-2 weeks for permits.
Will deepening affect my neighbors' wells?
Possible but usually minimal for residential wells. Deepening into different aquifers or significantly increasing pumping can affect nearby wells. Consider discussing with neighbors for larger projects.
Considering Well Deepening?
Southern California Well Service can assess your well and determine if deepening is a viable option. We'll inspect your casing, research local geology, and provide honest recommendations—whether that's deepening, hydrofracturing, or a new well.
