SC By SCWS Team | February 1, 2026 | 15 min read
Cost to Deepen an Existing Well: Complete 2026 Guide
Is your well running dry or producing less water than you need? Deepening your existing well can restore water supply at 30-50% less cost than drilling new. In San Diego County, well deepening typically costs $5,000 to $15,000+, depending on depth and conditions. Here's what determines your price.
💵 Well Deepening Cost Summary
- • Per-foot drilling: $75 - $150/foot
- • Mobilization fee: $1,500 - $3,000
- • Typical project (100 ft): $9,000 - $18,000
- • New casing (if needed): +$2,000 - $5,000
- • Pump reinstallation: $500 - $1,500
How Much Does Well Deepening Cost?
Well deepening costs vary based on several factors, but here's what San Diego County homeowners typically pay in 2026:
📊 Well Deepening Cost by Depth Added
50 Feet Additional
Minimum practical deepening
$5,000 - $9,000
100 Feet Additional ⭐ Most Common
Standard deepening project
$9,000 - $18,000
150 Feet Additional
Extended deepening
$13,000 - $25,000
200+ Feet Additional
Major deepening project
$17,000 - $35,000+
*Includes mobilization, drilling, and basic completion
Well Deepening Cost Breakdown
Understanding each component helps you evaluate quotes and plan your budget:
Mobilization Fee: $1,500-$3,000
This covers transporting the drill rig to your property, setup time, and preparation work. It's a fixed cost regardless of how much deepening is done, which is why deeper projects have better per-foot economics.
Per-Foot Drilling: $75-$150/foot
The drilling cost per foot depends on:
- Rock hardness: Hard granite costs more than sofite
- Existing well diameter: Smaller bores are harder to work in
- Depth already drilled: Deeper starting points increase difficulty
- Equipment required: Some wells need specialty tools
Casing Extension: $2,000-$5,000 (if needed)
If new casing is required to line the deepened section, costs include:
- Steel casing: $25-$50 per foot installed
- PVC casing: $15-$30 per foot installed
- Grouting and sealing: $500-$1,500
Not all deepening projects need new casing—stable rock formations often don't require it.
Pump Work: $500-$2,500
Your pump must be pulled before deepening and reinstalled after:
- Pump removal and reinstallation: $500-$1,500
- Additional drop pipe: $3-$8 per foot
- New pump (if needed for deeper setting): $800-$2,500
| Cost Component | Price Range | Notes |
|---|---|---|
| Mobilization | $1,500 - $3,000 | Fixed cost per project |
| Drilling per foot | $75 - $150 | Varies with rock hardness |
| Casing (if needed) | $2,000 - $5,000 | Not always required |
| Pump reinstallation | $500 - $1,500 | Required for all projects |
| Additional drop pipe | $3 - $8/foot | For new depth |
| Permits | $200 - $500 | County requirement |
When Can a Well Be Deepened?
Not every well is a good candidate for deepening. Here's what we evaluate:
Good Candidates for Deepening
- Casing in good condition: No holes, cracks, or severe corrosion
- Adequate diameter: 6" minimum for most drilling equipment
- Favorable geology: Water-bearing formations likely below
- Accessible location: Drill rig can reach the wellhead
- Original depth under 500 feet: Deeper wells are harder to extend
Poor Candidates for Deepening
- Damaged casing: Holes or corrosion compromise the well
- Narrow diameter: Under 5" limits equipment options
- Casing offset or crooked: Can't drill straight through
- Poor geology below: No water-bearing formations expected
- Contamination risk: Deepening could reach contaminated water
🔍 How to Know If Deepening Will Work
Before committing to deepening, we recommend a video camera inspection ($200-$400) to assess casing condition and a review of geological data. This small investment can save you from spending thousands on deepening a well that should be replaced.
Deepening vs. Drilling New: Cost Comparison
When water supply is inadequate, you have two options: deepen the existing well or drill a new one. Here's how the costs compare:
Cost Comparison: Same Property
Deepen Existing Well
Add 100 feet to 400-foot well
- Mobilization: $2,000
- Drilling (100 ft): $10,000
- Pump work: $1,200
- Permits: $300
Total: ~$13,500
Drill New Well
New 500-foot well
- Mobilization: $2,500
- Drilling (500 ft): $37,500
- Casing & development: $4,000
- Pump & equipment: $3,500
- Permits: $500
Total: ~$48,000
Deepening saves approximately $34,500 in this scenario
When to Choose Deepening
- Existing casing is in good condition
- Geology suggests water at greater depth
- Budget is limited
- Well location is ideal (near house, accessible)
- You need a faster solution
When to Choose New Well
- Existing casing is damaged or too narrow
- Current location has contamination issues
- Different location might yield more water
- Well is extremely old with unknown condition
- You want to keep the old well as backup
The Well Deepening Process
Understanding the process helps you know what to expect:
Step 1: Assessment (1-2 days)
- Review existing well records and logs
- Measure current depth and static water level
- Video inspection of casing condition
- Evaluate geology and water potential
- Provide quote with realistic expectations
Step 2: Preparation (1 day)
- Obtain necessary permits
- Pull existing pump and equipment
- Clean out debris from bottom of well
- Set up drill rig over wellhead
Step 3: Drilling (1-3 days)
- Drill through bottom of existing well
- Monitor for water production as drilling
- Continue to target depth or adequate water
- Install new casing if required
Step 4: Completion (1-2 days)
- Develop well to maximize production
- Test flow rate and recovery
- Reinstall pump at new depth
- Connect electrical and plumbing
- Final testing and adjustment
Total project time: 4-8 days for most deepening projects.
Factors That Affect Deepening Cost
1. Rock Type and Hardness
San Diego County has varied geology. Hard granite is common in the mountains and costs more to drill through than softer decomposed granite or sedimentary rock. Extremely hard rock can add 20-30% to drilling costs.
2. Existing Well Diameter
Larger diameter wells (8"+) are easier to work in and may cost less to deepen. Narrow wells (4-5") may require specialty equipment or may not be deepenable at all.
3. Current Well Depth
Deepening a 200-foot well is easier than deepening a 500-foot well. Greater existing depth means more time and complexity for each additional foot drilled.
4. Casing Requirements
If new casing is needed for the deepened section, costs increase significantly. Stable rock formations may not require casing, while fractured or unstable zones do.
5. Access and Location
Difficult access requiring smaller equipment or longer setup times adds cost. Remote locations may have additional travel charges.
Will Deepening Guarantee More Water?
No honest driller can guarantee results. However, experienced drillers can make educated assessments based on:
- Geological knowledge: Understanding local water-bearing formations
- Neighboring well data: What depths produce water nearby
- Your well's history: How water levels have changed over time
- Drought patterns: Whether low water is temporary or permanent
📊 What to Expect
In San Diego's fractured granite, deepening has roughly a 70-80% success rate when properly assessed beforehand. Success means meaningfully increased water production—though not necessarily as much as you might hope. We set realistic expectations before recommending deepening.
Alternatives to Well Deepening
Before committing to deepening, consider these alternatives:
Hydrofracturing ($3,000-$8,000)
High-pressure water injection can open existing fractures and create new pathways for water. Often tried before deepening as a less expensive option. Learn more in our hydrofracturing cost guide.
Well Rehabilitation ($2,000-$6,000)
Cleaning, acidizing, and redeveloping an existing well can restore lost production without drilling deeper. Effective when sediment or mineral buildup is reducing flow.
Storage Solutions ($3,000-$15,000)
Adding water storage tanks lets a slow well fill overnight and provide adequate pressure during the day. Doesn't increase production but can solve practical water availability issues.
Water Conservation
Reducing demand through efficient fixtures, smart irrigation, and water-wise landscaping may eliminate the need for more water production.
Frequently Asked Questions
How much does it cost to deepen a well?
Well deepening costs $5,000-$15,000+ in San Diego County. The price depends on current depth, additional depth needed, casing requirements, and rock conditions. Expect $75-$150 per foot for deepening, plus mobilization fees of $1,500-$3,000.
Can any well be deepened?
Not all wells can be deepened. Requirements include: casing in good condition, sufficient diameter (typically 6 inches minimum), favorable geology below current depth, and no obstructions. A video inspection can determine if your well is a candidate for deepening.
Is it better to deepen a well or drill a new one?
Deepening costs 30-50% less than a new well when feasible. However, drilling new is better when: the existing casing is damaged, the well is too narrow, there's no water-bearing formation below, or a different location might yield more water.
How much deeper can a well be drilled?
Most wells can be deepened 50-200 feet, depending on geology and equipment. The practical limit depends on the existing casing diameter and condition. Some wells have been successfully deepened 300+ feet, while others may only allow 50-100 feet of additional depth.
Will deepening my well guarantee more water?
No guarantee exists, but a qualified driller can assess the geology and make informed predictions. In San Diego's fractured rock, hitting additional water-bearing fractures at depth is common. We discuss realistic expectations before recommending deepening.
Is Well Deepening Right for You?
Don't guess—get an expert assessment. We'll evaluate your existing well, review local geology, and give you an honest recommendation on whether deepening makes sense or if another solution would be better. Free consultations available throughout San Diego County.
