Well Screen Replacement: Restoring Your Well's Water Production

Is your well producing less water than it used to? Are you seeing sand or sediment in your water? The problem might be your well screen. The well screen is the perforated section at the bottom of your well that allows water to enter while keeping sand and sediment out. When screens become clogged, corroded, or damaged, well screen replacement or rehabilitation can restore your well to full production.

Understanding Well Screens

A well screen is the intake portion of your well—the section with slots, holes, or perforations that allows groundwater to flow into the well while filtering out sand and gravel from the surrounding aquifer.

How Well Screens Work

In most San Diego and Riverside County wells, the screen is located at the bottom of the well casing, positioned in the water-bearing zone (aquifer). The screen's openings are sized to:

• Allow water to flow freely into the well
• Block sand and fine sediment from entering
• Provide structural support in unconsolidated formations
• Maximize contact with the aquifer for optimal water production

Types of Well Screens

Note: Many wells in our rocky San Diego County terrain are drilled into fractured bedrock and may not have traditional screens—water enters through natural fractures in the rock. These wells have different rehabilitation needs.

Signs Your Well Screen Needs Attention

Well screen problems develop gradually but can significantly impact your water supply. Watch for these warning signs:

Production Problems

• Declining yield: Well produces less water than before
• Slow recovery: Water level takes longer to rebound after pumping
• Lower specific capacity: Less gallons per minute per foot of drawdown
• Pump struggling: Motor working harder for same output
• Frequent pump cycling: Running out of water faster

Water Quality Issues

• Sand in water: Screen slots enlarged by corrosion or damage
• Sediment buildup: Fine particles passing through worn screen
• Turbid water: Cloudy appearance from suspended particles
• Pump damage: Abrasion from sand shortening pump life

Equipment Damage

• Worn pump impellers: Sand grinding away pump components
• Clogged pressure tank: Sediment accumulation
• Plugged water treatment: Filters overwhelmed by sediment

What Causes Well Screen Problems?

Encrustation and Clogging

The most common screen problem is gradual clogging from mineral deposits or biological growth:

• Mineral scale: Calcium carbonate, iron, and manganese deposits
• Iron bacteria: Slimy orange-brown bacterial buildup
• Sulfur bacteria: Black deposits with rotten-egg odor
• Fine sediment: Silt and clay particles filling slots

Iron bacteria is particularly common in San Diego County wells and can drastically reduce flow through screens. Learn more in our iron in well water guide.

Corrosion

Steel screens corrode over time, especially in aggressive water:

• Slot enlargement: Corrosion widens openings, allowing sand to pass
• Structural weakness: Screen loses strength and may collapse
• Complete failure: Holes develop beyond original slots

Physical Damage

• Pump installation damage: Equipment dropped or dragged
• Ground movement: Earthquakes or settling
• Over-pumping: Creating sand bridges that collapse into screen

Well Screen Rehabilitation Options

Before jumping to replacement, many screen problems can be addressed through rehabilitation:

Chemical Treatment

Acid and other chemicals can dissolve mineral scale and kill bacteria:

• Acidizing: Hydrochloric or sulfamic acid dissolves carbonate scale
• Chlorination: Kills bacteria and loosens biological buildup
• Polyphosphates: Disperse iron deposits
• Combination treatments: Multiple chemicals for complex fouling

Cost: $2,000 - $5,000

Effectiveness: Can restore 50-90% of lost capacity in suitable wells

Mechanical Cleaning

Physical methods to remove deposits and sediment:

• Wire brushing: Scrubs scale from screen surfaces
• High-pressure jetting: Blasts deposits with water
• Surging: Rapid water movement dislodges particles
• Bailing: Removes accumulated sediment from well bottom
• Airlifting: Uses compressed air to evacuate debris

Cost: $1,500 - $4,000

Best for: Sediment accumulation and light scale

Combined Rehabilitation

Most effective rehabilitation combines chemical and mechanical methods:

1. Camera inspection to assess condition
2. Remove pump and debris from well
3. Surge to loosen deposits
4. Chemical treatment (acid and/or chlorine)
5. Agitate to maximize chemical contact
6. Surge and bail to remove dissolved material
7. Develop well until water runs clear
8. Test yield and water quality
9. Reinstall pump

Cost: $3,000 - $8,000

Expected improvement: Often restores 60-95% of original capacity

When Screen Replacement Is Necessary

Rehabilitation isn't always enough. Screen replacement is needed when:

• Severe corrosion: Screen has holes beyond original slots
• Structural failure: Screen is crushed or collapsed
• Wrong slot size: Original screen doesn't match formation
• Rehabilitation failed: Chemical/mechanical treatment didn't restore production
• Sand pumping continues: Slots too enlarged to filter effectively

Screen Replacement Methods

Liner with New Screen

The most common approach for damaged screens:

• Install a smaller-diameter liner inside existing well
• New screen section at bottom of liner
• Seal between liner and old casing
• Does not require pulling old casing/screen

Cost: $5,000 - $12,000

Pros: Less invasive, faster, lower cost

Cons: Reduces well diameter (may require smaller pump)

Pull and Replace

In some cases, the old screen can be removed and replaced:

• Extract old casing and screen (if accessible)
• Install new casing and screen to original diameter
• Re-grout and develop well

Cost: $8,000 - $20,000+

Pros: Maintains full well diameter

Cons: More complex, not always possible

Deepen and Screen

If additional water-bearing zones exist below current screen:

• Drill deeper through existing well
• Install new screen section in deeper aquifer
• May increase production significantly

Cost: $10,000 - $25,000+

Pros: Can dramatically improve production

Cons: Requires suitable geology, higher cost

Well Screen Replacement Cost Factors

The Inspection and Assessment Process

Before recommending any treatment, we conduct a thorough assessment:

Step 1: History Review

• When was the well drilled?
• What's the construction (depth, casing, screen type)?
• What problems are you experiencing?
• When did problems start?
• Any previous rehabilitation work?

Step 2: Camera Inspection

A downhole video camera reveals:

• Screen condition (corrosion, encrustation, damage)
• Casing condition above screen
• Debris or sediment accumulation
• Water entry points
• Depth measurements

Step 3: Yield Testing

A pumping test measures current well performance:

• Gallons per minute production
• Drawdown during pumping
• Recovery rate
• Specific capacity calculation

Comparing current yield to original drilling records shows how much capacity has been lost. Learn more about this process in our well yield test guide.

Step 4: Water Quality Analysis

Testing identifies what's causing fouling:

• Iron and manganese levels
• Hardness (calcium/magnesium)
• pH (acidic water causes corrosion)
• Bacteria presence

Preventing Future Screen Problems

After rehabilitation or replacement, these practices extend screen life:

Service Areas

Southern California Well Service provides well screen services throughout:

Frequently Asked Questions