After the Storm: Well Inspection for Contamination

San Diego County experiences heavy rain events, flash floods, and occasional mudslides that can compromise private well safety. If your property experienced flooding, heavy runoff, or storm damage, your well water may be contaminated. This guide explains how to assess your well after a storm and what steps to take to ensure safe water.

When to Inspect Your Well After a Storm

Inspect Immediately If:

• Flooding reached the wellhead — Any standing water around the well cap
• Mudflow or debris — Mud, rocks, or vegetation deposited near the well
• Visible damage — Well cap displaced, wiring exposed, equipment knocked over
• Power surge or outage — May have damaged electrical components
• Nearby septic flooding — Septic system overflowed or was submerged

Inspect Within 24-48 Hours If:

• Heavy rain — More than 2-3 inches in 24 hours
• Flash flooding nearby — Even if your immediate area wasn't flooded
• Hillside erosion — Runoff patterns changed near the well
• Extended power outage — Pump wasn't running during the storm

Test Water Even Without Visible Damage If:

• Your well is less than 100 feet deep (shallow wells are vulnerable)
• The well is downhill from agricultural areas
• Heavy rain followed a wildfire (ash and debris contamination)
• You notice any change in water taste, color, or odor

How Storms Contaminate Wells

Surface Water Intrusion

The most common contamination pathway:

• Floodwater enters through a damaged or loose well cap
• Water flows down the outside of the well casing
• Cracked or deteriorated well seals allow surface water in
• Old dug wells with inadequate covers are especially vulnerable

Groundwater Contamination

Slower but can be widespread:

• Heavy rain pushes surface contaminants into the water table
• Rising groundwater levels bring shallow contamination to well depth
• Saturated septic systems release effluent into groundwater
• Agricultural runoff infiltrates aquifers

What Floodwater Contains

• Bacteria and viruses — E. coli, Salmonella, norovirus
• Sewage — From overflowing septic systems and sewer lines
• Animal waste — Livestock and wildlife contamination
• Chemicals — Pesticides, fertilizers, fuel, household chemicals
• Sediment — Sand, silt, organic matter
• Debris — Leaves, insects, small animals

Post-Storm Inspection Checklist

Safety First

• ☐ Don't approach the well if floodwater is still present
• ☐ Don't touch electrical equipment if wet or damaged
• ☐ Turn off power at the breaker before inspecting
• ☐ Assume the water is contaminated until tested

Visual Inspection

• ☐ Check well cap — Is it in place and sealed?
• ☐ Look for debris — Mud, vegetation, or foreign material at the wellhead
• ☐ Check casing — Any visible cracks or damage at surface level
• ☐ Inspect wiring — Is the conduit intact? Any exposed wires?
• ☐ Check pressure tank — Any damage, leaning, or displacement
• ☐ Look at the control box — Signs of water intrusion or damage
• ☐ Check surrounding area — Erosion, new drainage patterns, standing water

Water Quality Quick Check

Before professional testing, note:

• ☐ Color — Is it clear, cloudy, brown, or discolored?
• ☐ Odor — Any unusual smell (sewage, chemical, sulfur, musty)?
• ☐ Particles — Visible sediment or floating material?

Testing After a Storm

Recommended Test Panel

Additional Testing If Needed

• VOCs — If fuel or chemical contamination suspected
• Pesticides — If flooding came from agricultural areas
• Heavy metals — If industrial contamination possible

Testing Procedure

1. Run the pump for 5-10 minutes to flush stagnant water
2. Collect sample in sterile container (lab provides)
3. Keep sample cool (not frozen) and deliver to lab within 24 hours
4. For bacteria testing, faster is better—bacteria counts change over time

If Your Well Is Contaminated

Immediate Steps

1. Stop drinking the water — Use bottled water for drinking and cooking
2. Limit use — Bathing is generally safe; don't use for food prep
3. Don't run dishwasher or ice maker — Uses contaminated water
4. Notify household members — Including tenants, guests

Disinfection (Shock Chlorination)

The standard treatment for bacterial contamination:

What You Need

• Unscented household bleach (5.25-6% sodium hypochlorite)
• Or calcium hypochlorite granules (pool shock)
• Calculator for chlorine amount (based on well depth and diameter)
• Clean bucket for mixing
• Garden hose to circulate water

Chlorine Amount (Using Household Bleach)

Disinfection Steps

1. Remove well cap and inspect for debris
2. Remove debris if present
3. Mix chlorine with 3 gallons of water in a bucket
4. Pour solution into well
5. Connect hose to outdoor faucet and put other end into well
6. Run pump for 15-20 minutes to circulate chlorine
7. Open each faucet until you smell chlorine, then close
8. Include water heater, washing machine, dishwasher connections
9. Let sit 12-24 hours — Don't use water during this time
10. Flush the system — Run outside faucet until chlorine smell is gone
11. Flush indoor faucets one by one
12. Wait 7 days before retesting for bacteria

When Shock Chlorination Isn't Enough

Consider professional help if:

• Bacteria returns after shock chlorination
• Well was submerged in floodwater
• Physical damage to the well
• Contamination source is ongoing (septic failure, etc.)
• Chemical contamination detected

Preventing Storm Contamination

Well Protection Measures

• Sanitary well cap — Watertight, vermin-proof cap
• Proper grading — Ground slopes away from wellhead
• Wellhead above grade — At least 12 inches above ground
• Intact casing seal — No gaps where surface water can enter
• Backflow prevention — On irrigation and hose connections

Before Storm Season

• Inspect well cap and replace if damaged
• Check casing for cracks or deterioration
• Verify grading directs water away from well
• Clear debris from around wellhead
• Know how to shut off power to the pump
• Have bottled water stored for emergencies

Frequently Asked Questions

Our Post-Storm Services

Southern California Well Service provides emergency response after storms:

• Emergency inspection — Assess damage and contamination risk
• Water testing — Coordinated with certified labs
• Professional disinfection — Thorough shock chlorination
• Well repair — Fix caps, seals, and damaged equipment
• Pump service — If electrical damage occurred
• Well rehabilitation — For severe contamination cases