By SCWS Team | February 4, 2026
12 min read
Your shower pressure isn't what it used to be. The sprinklers barely reach the far edges of your lawn. You notice the pump running longer before the pressure tank fills. Something's changed—your well isn't producing as much water as before. This is a common concern for San Diego, Riverside, and San Bernardino County well owners, especially during California's frequent drought cycles. The good news: declining well yield has multiple potential causes, and most are fixable. The key is accurate diagnosis.
💡 Important Distinction: A well producing less water is different from a well with no water. If your well has stopped completely, see our emergency no-water guide. This article addresses gradual decline in water production.
Diagnosing the Problem: Pump vs. Well
Before spending money on solutions, determine whether the problem is your pump (mechanical) or your well (geological). The symptoms differ:
Signs It's a Pump Problem
- Consistently low pressure throughout the day, regardless of usage
- Pump runs but doesn't build pressure
- Unusual pump noises (grinding, clicking, humming)
- Tripping circuit breaker
- Pump runs continuously without shutting off
- Water sputters or sprays air initially
- Problem appeared suddenly, not gradually
Signs It's a Well Problem
- Good initial flow that weakens during extended use
- Water pressure recovers after the well "rests" for a period
- Gradual decline over months or years
- Sediment or sand appearing in water
- Changes in water color, taste, or smell
- Problem worsens during drought conditions
- Neighbors reporting similar issues
Common Causes of Declining Well Yield
1. Worn or Failing Pump
Submersible well pumps typically last 8-15 years. As they age, impellers wear, seals degrade, and motor efficiency drops. A pump that once delivered 10 gallons per minute might decline to 5 GPM or less.
Signs:
- Pump is over 10 years old
- Higher electricity bills (working harder for less water)
- Pump runs longer to fill pressure tank
- Visible sand or sediment (worn impellers pass debris)
Solution: Pump replacement. Cost: $1,500-3,500 depending on well depth and pump capacity.
2. Clogged or Encrusted Well Screen
The well screen (perforated section at the bottom that allows water in) can become blocked by mineral buildup, sand, silt, or bacterial slime over time. This is extremely common in Southern California's mineral-rich water.
Signs:
- Gradual decline over several years
- Hard water (high mineral content)
- Well has never been cleaned/rehabilitated
- Reduced flow but pump performs normally
Solution: Well rehabilitation using chemical treatment (acid or chlorine), mechanical brushing, or air-burst development. Cost: $1,000-5,000.
3. Biofouling (Iron Bacteria)
Iron bacteria are naturally occurring organisms that feed on iron in groundwater. They create a reddish-brown slime that coats well screens, pumps, and piping, gradually choking off water flow.
Signs:
- Reddish-brown or orange slime in toilet tanks
- Musty, earthy, or "swampy" odor
- Visible stringy material in water
- Iron-rich water (stains fixtures)
Solution: Aggressive chlorination treatment (shock chlorination), followed by ongoing preventive treatment. May need to combine with physical well cleaning. Cost: $500-3,000.
4. Lowered Water Table (Drought Impact)
During California's drought cycles, groundwater levels drop as recharge from rainfall decreases while pumping continues. If your pump sits near the water level, yield declines or the pump can start sucking air.
Signs:
- Problem coincides with drought conditions
- Neighbors experiencing similar issues
- Air spurting from faucets during heavy use
- Recovery after rest periods
- Worse during summer high-use months
Solutions:
- Lower the pump: If water level dropped but well is deep enough, repositioning pump may help ($500-1,500)
- Deepen the well: Extend casing and drill deeper ($50-150/foot)
- Hydrofracturing: Open new fractures in rock to improve water access ($2,000-6,000)
- Drill new well: If current well location is depleted ($15,000-50,000)
📊 Southern California Water Table Reality
Many parts of San Diego, Riverside, and San Bernardino Counties have experienced significant groundwater decline. The Borrego Valley, for example, has seen water levels drop over 100 feet since 1945. Less dramatic but still significant drops affect areas throughout the region, especially in agricultural zones like Valley Center, Fallbrook, and Temecula.
5. Well Casing Damage
The well casing (steel or PVC pipe lining the well bore) can deteriorate, collapse, or develop holes over time. This can allow sand and sediment to enter, reduce structural integrity, or compromise the seal against surface contamination.
Signs:
- Sand or sediment in water
- Well is over 30-40 years old
- Sudden change in water quality
- Pump getting stuck or difficult to pull
Solution: Video inspection to assess damage. Minor repairs possible with casing liners; severe damage may require a new well.
6. Increased Water Demand
Sometimes the well hasn't changed—your water usage has. Home additions, new irrigation systems, more people in the household, or livestock can exceed what your well can sustainably produce.
Signs:
- Problem appeared after lifestyle changes
- Well performs fine with light use but not heavy
- Original well sized for smaller household/property
Solutions:
- Install storage tank to buffer demand
- Reduce usage through conservation
- Upgrade to higher-capacity pump (if well supports it)
- Drill additional well for irrigation
Professional Diagnosis: The Yield Test
The most accurate way to diagnose declining well yield is a professional pump/draw-down test. Here's what it involves:
- Measure static water level: Water level with pump off and well at rest
- Run pump at known rate: Measure actual pump output (GPM)
- Measure pumping water level: How far water drops during pumping
- Calculate draw-down: Difference between static and pumping levels
- Recovery test: How quickly water level recovers when pump stops
This data reveals whether the problem is pump performance (low GPM output), well capacity (excessive draw-down), or aquifer recharge (slow recovery). Cost for professional testing: $200-500.
Solutions by Cause: Quick Reference
| Cause | Solution | Typical Cost |
|---|---|---|
| Worn pump | Pump replacement | $1,500-3,500 |
| Clogged screen | Well rehabilitation | $1,000-5,000 |
| Iron bacteria | Chlorination + cleaning | $500-3,000 |
| Lowered water table | Lower pump, deepen well, or hydrofrac | $500-6,000+ |
| Casing damage | Liner or new well | $2,000-50,000 |
| Demand exceeds capacity | Storage tank or second well | $2,000-50,000 |
Preventing Future Yield Decline
Once you've addressed the current problem, take steps to prevent recurrence:
- Annual pump inspection: Catch wear before failure
- Periodic well rehabilitation: Clean screen every 10-15 years in hard water areas
- Monitor water levels: Install water level indicator or have tested periodically
- Conserve during drought: Reduce irrigation, fix leaks, stagger high-use activities
- Maintain proper well seal: Prevent surface contamination that feeds bacteria
- Water quality testing: Iron bacteria caught early is easier to treat
✓ Action Plan for Declining Well Yield
- 1. Observe symptoms – Note when problem occurs and how severe
- 2. Check pressure tank – Rule out pressure tank issues (how-to guide)
- 3. Schedule professional evaluation – Yield test + pump inspection
- 4. Get diagnosis and options – Compare repair vs. replacement costs
- 5. Address root cause – Not just symptoms
- 6. Plan preventive maintenance – Avoid repeat problems
Is Your Well Producing Less Water?
Don't wait until you have no water. Southern California Well Service diagnoses and resolves declining well yield throughout San Diego, Riverside, and San Bernardino Counties. From pump testing to well rehabilitation to hydrofracturing, we have the equipment and expertise to restore your water production.
See also: Learn about understanding your well's GPM flow rate for your property.
