Well Grouting & Sealing: Why It Matters

What Is Well Grouting?

The Concept

• Borehole is drilled larger than casing
• Casing is installed
• Gap between casing and borehole wall remains
• Grout fills this gap (annular space)
• Creates seal from surface to sealing depth

Annular Space

The gap (annular space) is typically 2-4 inches all around the casing. Without sealing, this is a direct pathway for contamination.

Components of Well Sealing

• Grout: Material filling annular space
• Well cap: Covers top of casing
• Casing: Pipe lining the well
• Surface seal: Concrete pad around wellhead

Why Grouting Matters

Protection From Contamination

• Prevents surface water from entering well
• Blocks runoff (fertilizers, pesticides, animal waste)
• Stops bacteria migration
• Seals off shallow contaminated water

Structural Support

• Stabilizes casing
• Prevents shifting or settling
• Protects casing from corrosion

Legal Compliance

• Required by California well standards
• County permits specify requirements
• Inspected during well construction

Consequences of Poor Sealing

• Bacteria in water
• Nitrate contamination
• Chemical contamination
• Failed water tests
• Health risks

Requirements

California General Requirements

• Minimum 20 feet of surface seal
• May require more depending on conditions
• Must seal off contaminated zones
• Materials must meet standards

San Diego County

• Follows state standards
• Permit specifies depth based on site
• Inspection required

When More Depth Required

• Near septic systems
• Contaminated shallow zones present
• Fractured rock (faster pathways)
• Adjacent to pollution sources

Surface Seal

• Concrete pad around wellhead
• Typically 4 feet diameter, 4 inches thick
• Slopes away from casing
• Prevents ponding at wellhead

Grouting Materials

Cement Grout

• Portland cement mixed with water
• May include bentonite or sand
• Very durable
• Permanent seal
• Most common for new wells

Bentonite

• Natural clay that swells when wet
• Available as chips, pellets, or grout
• Good seal when hydrated
• Easier to place than cement
• Used where cement is difficult

Placement Methods

• Tremie: Pipe delivers grout to bottom, fills upward
• Dump: Grout poured from surface (shallow applications)
• Pressure: Grout pumped under pressure

Grout Mix

• Not regular concrete—no large aggregate
• Must flow to fill annular space
• Specific water-to-cement ratio
• May include additives for pumpability

Grouting Problems

Signs of Poor Sealing

• Bacteria in water (repeated positive tests)
• Nitrates present
• Water quality changes with rain
• Surface water characteristics
• Water muddy after storms

Old Wells

• May not meet current standards
• May have minimal or no grouting
• Deteriorated over time
• Consider inspection if contamination issues

Common Issues

• Grout didn't reach full depth
• Gaps or voids in grout
• Grout shrinkage/cracking
• Settlement of fill material

Repair Options

Re-Grouting

• Pressure grout into existing annular space
• May fill voids and gaps
• Limited if original was poorly done

Casing Repair

• Insert liner inside existing casing
• Seal the liner in place
• Creates new seal

Wellhead Improvement

• New sanitary well cap
• Concrete surface seal
• Proper grading away from well

When New Well Needed

• Extensive structural problems
• Unable to seal effectively
• Cost of repair approaches new well cost

Cost Estimates

• Re-grouting: $500-$2,000
• Surface seal repair: $300-$800
• Casing liner: $2,000-$8,000

We service all major pump brands including Franklin Electric, Grundfos, Goulds (Xylem), and Sta-Rite (Pentair). Our trucks carry common parts and components for same-day repairs.

Frequently Asked Questions

What is well grouting and why is it important?

Grouting seals the gap between casing and borehole. It prevents contamination from reaching your water. Required by code.

How deep should grouting be?

California requires minimum 20 feet, more if needed to seal contaminated zones. Your permit specifies requirements.

Can an old well be re-grouted?

Sometimes. Pressure grouting can fill voids. Effectiveness depends on existing conditions. Professional inspection needed.

How do I know if my well is properly sealed?

New wells are inspected. Old wells: if water tests show bacteria/nitrates repeatedly, sealing may be compromised. Camera inspection can help.

What's the difference between cement and bentonite grout?

Cement is more permanent and durable. Bentonite swells to seal and is easier to place in some situations. Both are approved materials.