By SCWS Team
January 30, 2026 · 12 min read
Your well water could contain invisible dangers—and you'd never know without testing. Unlike municipal water systems that undergo continuous monitoring, private well safety falls entirely on the homeowner. This comprehensive guide walks you through exactly what to test for, when to test, and how to interpret results—protecting your family with knowledge.
Why Well Water Testing Matters
Private wells serve approximately 15% of Americans, and in rural San Diego County communities like Ramona, Julian, and Valley Center, that percentage is much higher. While well water is often naturally pure and great-tasting, contaminants can enter your water supply without any obvious signs. The California well owner resources page provides additional guidance on maintaining safe drinking water.
Groundwater contamination can come from many sources:
- Natural sources: Minerals, bacteria, and naturally occurring arsenic or radon
- Agricultural runoff: Fertilizers, pesticides, and animal waste
- Septic systems: Bacteria and nitrates from nearby or failing systems
- Industrial activity: Chemicals, heavy metals, and solvents
- Well construction issues: Cracked casings, improper seals, or aging components
The scary part? Many dangerous contaminants have no taste, color, or odor. The only way to know your water is safe is through laboratory testing.
What to Test Your Well Water For
Not all contaminants require the same testing frequency. Here's a breakdown of what to test for and why:
Priority Contaminants (Test Annually)
Coliform Bacteria
Total coliform bacteria indicate whether disease-causing organisms may be present. While most coliform bacteria are harmless, their presence suggests a pathway exists for dangerous pathogens to enter your well.
Safe level: 0 (absent) | Action if detected: Retest, then shock chlorinate if confirmed
E. coli Bacteria
E. coli specifically indicates fecal contamination from human or animal waste. This is a serious health concern requiring immediate action.
Safe level: 0 (absent) | Action if detected: Stop drinking water immediately, disinfect well
Nitrates
Common in agricultural areas, nitrates come from fertilizers, septic systems, and animal waste. High nitrate levels are particularly dangerous for infants (causing "blue baby syndrome") and pregnant women.
Safe level: Below 10 mg/L | Action if elevated: Install reverse osmosis system, identify source
Secondary Contaminants (Test Every 3-5 Years)
These affect water quality, taste, and appliance longevity but typically don't pose immediate health risks:
| Contaminant | Recommended Level | Issues if Elevated |
|---|---|---|
| pH | 6.5 - 8.5 | Corrosion, metallic taste, plumbing damage |
| Hardness | <120 mg/L (ideal) | Scale buildup, soap inefficiency, appliance damage |
| Iron | <0.3 mg/L | Staining, metallic taste, clogged pipes |
| Manganese | <0.05 mg/L | Black staining, bitter taste |
| Total Dissolved Solids | <500 mg/L | Salty taste, mineral buildup |
| Sulfates | <250 mg/L | Laxative effect, bitter taste |
| Chloride | <250 mg/L | Salty taste, corrosion |
Special Concern Contaminants (Test Based on Location)
Certain areas of San Diego County have elevated risks for specific contaminants:
- Arsenic: Naturally occurring in some groundwater—particularly a concern in parts of East County. Test if you haven't had a baseline.
- Lead: Usually from old plumbing, not the well itself. Test if you have older pressure tanks or brass fittings.
- Radon: A radioactive gas that can dissolve into groundwater. Test if radon is elevated in your area.
- Pesticides/Herbicides: Important if you're near agricultural operations or orchards.
- VOCs (Volatile Organic Compounds): Test if near industrial sites, gas stations, or dry cleaners.
Not sure what's in your area? Our team can advise on location-specific testing recommendations during a well inspection.
How Often Should You Test?
The EPA and California Department of Public Health recommend the following testing schedule for private well owners:
Recommended Testing Schedule
- Annually: Coliform bacteria, nitrates, and any contaminants of local concern
- Every 3-5 years: Comprehensive mineral panel (pH, hardness, iron, manganese, TDS)
- Once (baseline): Heavy metals, arsenic, radon (especially for new wells or new homeowners)
- As needed: When you notice changes in water quality
When to Test Immediately
Beyond regular schedules, test your well water right away if you experience:
- Changes in taste, color, or odor
- Gastrointestinal illness in your household
- After flooding or heavy rainfall that may have affected your wellhead
- Following an earthquake (common in Southern California)
- Nearby construction or land disturbance
- A known contamination event in your area
- After any well repair work
- When purchasing a home with a well
DIY Testing vs. Professional Laboratory Testing
You have two main options for testing your well water: at-home test kits or certified laboratory analysis. Here's how they compare:
DIY Home Test Kits
Cost: $20-$50 for basic kits, $100-$150 for comprehensive kits
Best for: Quick screening, monitoring between professional tests, hardness/pH checks
Pros:
- Immediate results (minutes to hours)
- Convenient—no sample shipping
- Good for regular monitoring
- Inexpensive per test
Cons:
- Less accurate than lab testing
- Limited contaminant detection
- Results may be hard to interpret
- Not suitable for bacteria or nitrate confirmation
Certified Laboratory Testing
Cost: $30-$500 depending on panel (see detailed costs below)
Best for: Annual bacteria/nitrate testing, comprehensive analysis, real estate transactions
Pros:
- Highly accurate, certified results
- Detects precise contamination levels
- Results hold up for official purposes
- Professional interpretation often included
Cons:
- Takes 3-10 days for results
- Requires proper sample collection
- Higher per-test cost
Our recommendation: Use laboratory testing for annual bacteria/nitrate tests and comprehensive panels. DIY kits are great for monitoring pH and hardness between professional tests, but shouldn't replace lab testing for health-critical contaminants.
Well Water Testing Costs in San Diego
Testing costs vary based on what you're testing for and whether you collect the sample yourself:
| Test Type | Self-Collected Sample | Professional Collection |
|---|---|---|
| Bacteria (coliform/E. coli) | $30 - $50 | $75 - $125 |
| Nitrates only | $25 - $40 | $70 - $100 |
| Basic panel (bacteria, nitrates, pH, hardness) | $100 - $150 | $150 - $225 |
| Standard panel (+ minerals, TDS) | $150 - $250 | $200 - $350 |
| Comprehensive (+ heavy metals) | $250 - $400 | $350 - $500 |
| Full panel (+ pesticides, VOCs) | $400 - $600 | $500 - $750 |
Where to Get Your Water Tested in San Diego
- San Diego County DEH: Offers bacteria testing and can recommend certified labs
- State-certified laboratories: Search California's ELAP-certified lab list
- Local water testing companies: Many offer sample pickup and delivery
- Well service companies: We can coordinate testing as part of well inspections
📅 Minimum Testing Schedule
Annually: Bacteria + Nitrates ($50-$100) | Every 3-5 Years: Comprehensive mineral panel ($150-$300) | After ANY well work: Full retest
How to Collect a Water Sample
Proper sample collection is critical for accurate results. Here's how to do it right:
For Bacteria Testing
- Use only a sterile container provided by the lab—don't substitute
- Choose an indoor faucet without aerator, filter, or water treatment
- Clean the faucet with bleach solution, then let water run for 2-3 minutes
- Open the sterile container without touching the inside
- Fill to the indicated line—don't overfill
- Cap immediately and keep cold (ice pack, not frozen)
- Deliver to lab within 24 hours (6 hours is ideal)
For Chemical/Mineral Testing
- Use containers provided by the lab
- Run water for 2-3 minutes before collecting
- Fill completely, leaving no air space (unless instructed otherwise)
- Some tests require sample preservation—follow lab instructions exactly
- Label with date, time, and sample location
Timing matters: Collect samples in the morning before heavy water use, and plan to deliver them the same day.
Understanding Your Test Results
Lab reports can be confusing. Here's how to interpret the key results:
Bacteria Results
- "Absent" or "Not Detected": Congratulations—your water is bacteriologically safe
- "Present" or positive coliform: Contamination pathway exists—retest, then treat if confirmed
- E. coli positive: Serious—stop drinking immediately and contact a professional
Nitrate Results
- 0-5 mg/L: Excellent—well below concern
- 5-10 mg/L: Acceptable but monitor annually
- Above 10 mg/L: Exceeds EPA limit—don't give to infants, investigate source, consider treatment
pH Results
- Below 6.5: Acidic—may corrode pipes and leach metals
- 6.5-8.5: Ideal range
- Above 8.5: Alkaline—may cause scale and affect taste
Hardness Results
- 0-60 mg/L: Soft water
- 61-120 mg/L: Moderately hard
- 121-180 mg/L: Hard water—consider softener
- Above 180 mg/L: Very hard—water softener recommended
San Diego County well water tends to be hard due to our mineral-rich geology. Compare your options with our guide on well water vs city water in California.
What To Do If Your Water Fails a Test
A failed test doesn't mean your well is ruined. Here are typical solutions for common problems:
Bacteria Contamination
- Retest to confirm (false positives happen)
- If confirmed, shock chlorinate the well
- Retest 1-2 weeks after treatment
- If bacteria returns, investigate well integrity—may need well repair
High Nitrates
- Install reverse osmosis system for drinking water
- Identify and eliminate source (septic, fertilizer)
- In severe cases, may need a deeper well to reach uncontaminated water
Hard Water / Mineral Issues
- Water softener for hardness
- Iron filter for iron/manganese staining
- Acid neutralizer for low pH
Frequently Asked Questions
How often should I test my well water in San Diego?
Test your well water at least once per year for bacteria (coliform) and nitrates. Test every 3-5 years for a comprehensive panel including minerals, pH, and other contaminants. Additional testing is recommended after flooding, earthquakes, changes in taste/odor, nearby construction, or if anyone in the household becomes ill.
How much does well water testing cost in San Diego?
Basic bacteria testing costs $30-$50 at local labs. Standard panels including bacteria, nitrates, and basic minerals run $100-$200. Comprehensive testing covering heavy metals, pesticides, and VOCs costs $300-$500. Professional testing services that include sample collection typically add $50-$100 to these costs.
What should I test my well water for?
At minimum, test annually for coliform bacteria and nitrates—the two most common well water contaminants. Every 3-5 years, test for pH, hardness, iron, manganese, total dissolved solids (TDS), and sulfates. Consider testing for arsenic, lead, and other heavy metals if you live in certain areas of San Diego County or have older well components.
Can I use a DIY well water test kit?
DIY test kits ($20-$50) are useful for basic screening of pH, hardness, and some contaminants, but they're not as accurate as certified lab testing. For bacteria and nitrates—the most critical health-related tests—always use a certified laboratory. DIY kits are best for monitoring between professional tests, not as a replacement.
What do I do if my well water test shows contamination?
Don't panic—many contamination issues have straightforward solutions. For bacteria, shock chlorination often resolves the problem. High nitrates may require a reverse osmosis system. Hard water or iron can be treated with water softeners or filtration. Contact a well professional to discuss treatment options based on your specific test results and contamination levels.
Need Help With Your Well Water?
Whether you need help interpreting test results, treating contamination, or scheduling a comprehensive well inspection, we're here to help. Our experienced technicians serve all of San Diego County and can recommend the right testing and treatment for your specific situation.