How do I protect my well from contamination?

Key protection measures: maintain a secure well cap and sanitary seal, keep hazardous materials 100+ feet from well, properly maintain septic system, ensure proper grading so surface water drains away, control vegetation around wellhead, avoid using pesticides/fertilizers near well, test water annually for bacteria and periodically for other contaminants, inspect well components regularly, and properly dispose of hazardous waste—never dump near well.

What should I do if my well is contaminated?

First, stop drinking the water and switch to bottled water. Then: identify the type of contamination through testing, find and eliminate the contamination source if possible, disinfect the well (shock chlorination for bacteria), retest after treatment, consider ongoing treatment systems if contamination persists or is from natural sources. For serious contamination or unknown sources, consult a professional. Document everything for potential insurance or legal claims.

Preventing Well Contamination: Complete Protection Guide

Q: What can contaminate a private well?

Common contamination sources include: septic system failure or improper placement, agricultural runoff (fertilizers, pesticides, animal waste), surface water infiltration through damaged well components, naturally occurring contaminants (arsenic, radon, bacteria), nearby fuel storage tanks, improper chemical storage or disposal, flooding events, and improperly abandoned wells that provide pathways for contamination. Some contamination is preventable through proper well and property management; other sources require treatment.

Q: How far should a well be from a septic system?

California requires a minimum 50-foot separation between wells and septic tanks, with 100 feet from leach fields. Some counties require greater distances—San Diego County requires 100 feet from any septic component. In fractured rock or highly permeable soil, even these distances may be insufficient. New well installation should maximize distance from septic systems. If you have an existing well closer than these distances, more frequent water testing is advisable.

Q: What are signs my well may be contaminated?

Warning signs include: changes in taste, odor, or color, cloudiness or floating particles, staining of fixtures (iron, manganese), digestive illness in household members after drinking water, positive bacteria test after previously testing negative, oily sheen on water surface, unusual foam or bubbles. Any of these warrants immediate water testing. Note that many contaminants (arsenic, nitrates, many bacteria) have no visible signs—testing is the only way to detect them.

Unlike public water systems, no one is testing or protecting your private well except you. Contamination can happen gradually or suddenly, from sources you control and sources you can't. Understanding the threats—and how to prevent them—is essential for safe drinking water.

Common Contamination Sources

On Your Property

Septic systems: #1 source of bacteria contamination in private wells
Fuel storage: Underground tanks can leak; above-ground tanks can spill
Fertilizers & pesticides: Can leach through soil to groundwater
Animal waste: Horses, chickens, dogs near wellhead
Old wells: Improperly abandoned wells create contamination pathways
Vehicle maintenance: Oil, antifreeze, solvents

Neighboring Properties

Agricultural operations: Fertilizers, pesticides, animal waste
Industrial sites: Chemical storage and disposal
Gas stations: Underground storage tanks
Neighbors' septic systems: Especially if uphill from your well
Road runoff: Salt, oil, chemicals from paved surfaces

Natural Sources

Arsenic: Naturally present in certain California geology
Uranium & radon: From radioactive minerals in rock
Nitrates: Can be natural or from agriculture
Iron & manganese: Naturally occurring; not health hazards but nuisances
Bacteria: Can be natural or from contamination

Setback Distance Requirements

Potential Contamination Source	Minimum Distance from Well
Septic tank	50-100 feet (varies by county)
Septic leach field	100-150 feet
Underground fuel tank	100 feet minimum
Livestock/animal areas	100 feet
Fertilizer/pesticide storage	100 feet
Property boundary	5-10 feet (varies)
Surface water bodies	50-100 feet

Wellhead Protection

✓ Wellhead Protection Checklist

Secure well cap: Vermin-proof, properly sealed
Sanitary seal: Intact where pipes/wires enter
Proper grading: Surface slopes away from well
12" casing height: Extends above ground level
No debris: Keep vegetation and mulch away from casing
Protective bollards: Prevent vehicle damage if near driveway
Clear zone: No pesticides, fertilizers, chemicals within 100 feet

Septic System Management

Your septic system is probably the biggest contamination threat you control:

Pump regularly: Every 3-5 years for typical household use
Don't overload: Spread laundry loads; fix leaky fixtures
Avoid harmful inputs: No grease, chemicals, excessive antibacterials
Inspect annually: Catch problems before they reach groundwater
Know the location: Don't park or build over leach field
Watch for signs: Slow drains, wet spots, odors indicate problems

Chemical & Fuel Management

Store away from well: 100+ feet for any hazardous materials
Secondary containment: Place fuel containers in catch basins
Dispose properly: Never dump chemicals, oil, or pesticides on ground
Use carefully: Mix pesticides/herbicides away from well area
Inspect tanks: Check for leaks on any fuel storage

Flood and Storm Protection

Before storms: Verify cap and seal are secure
During flooding: Don't use well if water covers wellhead
After flooding: Assume contamination; disinfect before use
Inspect damage: Check all components after severe weather
Test water: Always test after flooding events

See our complete flood disinfection guide for emergency procedures.

Water Testing Program

Regular testing catches problems early:

Bacteria: Test annually (minimum)
Nitrates: Annually if near agriculture or septic
Comprehensive panel: Every 3-5 years
After incidents: Test after flooding, nearby contamination events, or water quality changes

Frequently Asked Questions

What can contaminate a private well?

Common sources include septic systems, agricultural runoff, surface water infiltration, naturally occurring contaminants (arsenic, radon), fuel tanks, chemical storage, flooding, and improperly abandoned wells.

How far should a well be from a septic system?

California requires minimum 50 feet from septic tanks, 100 feet from leach fields. Some counties require more. San Diego County requires 100 feet from any septic component.

What are signs my well may be contaminated?

Warning signs include taste/odor/color changes, cloudiness, fixture staining, digestive illness, and positive bacteria tests. However, many contaminants have no visible signs—testing is essential.

Need Help Protecting Your Well?

Southern California Well Service provides inspection, maintenance, and water quality services throughout San Diego and Riverside Counties.

Call (760) 463-0493

Preventing Well Contamination