Post-Flood Well Disinfection in South Carolina: The New SCDES Hotline and the CDC Protocol

Hurricane Helene's impact on South Carolina in 2024, 49 deaths, approximately 5,000 homes damaged, 21 tornadoes, and widespread inland flooding, exposed how many private well owners are unprepared for post-flood water contamination. Wells that flood become presumptively contaminated. Drinking, cooking, or brushing teeth with flood-affected well water without proper disinfection and retesting is a real health risk. This article covers the current South Carolina regulatory framework (which changed mid-2024), the CDC-recommended shock chlorination protocol, and the practical steps to safely return a flooded well to service.

The SCDHEC → SCDPH / SCDES Split

Effective July 1, 2024, the long-standing South Carolina Department of Health and Environmental Control (SCDHEC) was split into two new agencies. Bill signed by Governor McMaster; announced June 24, 2024:

• SC Department of Public Health (SCDPH): Health Promotion & Services; Healthcare Quality
• SC Department of Environmental Services (SCDES): Five bureaus, Air Quality, Coastal Management, Land & Waste, Water (includes private well program, hydrology from former DNR), Regional Lab Services
• Retail food and milk/dairy lab work moved to the SC Department of Agriculture

SCDES Private Well Hotline

For private well-related questions, bacterial testing resources, and post-flood guidance, the current contact is:

SCDES Private Well Hotline: 1-888-761-5989

SCDES activated this hotline during Hurricane Helene recovery in 2024 and maintains it as the primary state-level resource for private well owners.

The CDC Shock Chlorination Protocol

The CDC's published procedure for post-flood well disinfection:

1. Do not use the well for drinking, cooking, brushing teeth, or bathing until testing confirms safety.
2. Use bottled water or boiled water in the interim. Boiling: rolling boil for at least 1 minute.
3. Inspect the wellhead for damage, displaced cap, standing water near casing, visible cracks.
4. Pump out at least 3 well volumes (or approximately 1 hour of continuous pumping) to flush flood-contaminated water.
5. Shock chlorinate using unscented household bleach (~5.25% sodium hypochlorite) targeting approximately 500 mg/L free chlorine. Open all fixtures until you smell chlorine. Let sit 12+ hours.
6. Flush the system by running water until chlorine odor is gone (can take hours, even days for deep wells).
7. Wait 7–10 days after disinfection before retesting, allows residual chlorine to dissipate and any surviving bacteria to regrow to detectable levels.
8. Collect coliform + E. coli samples. Two clean samples 24 hours apart is a common EPA/extension protocol; verify with SCDES or CDC language for specific SC requirements.

Dosing by Casing Diameter

Standing water volume determines how much bleach to use:

• 4-inch casing: ~0.65 gallons of water per foot of water column
• 6-inch casing: ~1.47 gallons per foot
• Standard dose: approximately 3 pints of 5.25% bleach per 100 gallons of standing water, targeting ~500 mg/L free chlorine

Verify exact dosing tables against SCDES, CDC, Penn State Extension, UGA, or Maine CDC sources before executing. Over-dosing wastes bleach without improving results; under-dosing leaves pathogens alive.

When to Call a Professional

Shock chlorination is within reach for most homeowners, but call a licensed well contractor or water treatment company if:

• Visible casing damage, displaced cap, or wellhead submerged during flood
• Cloudy or discolored water that does not clear after extended flushing
• Multiple post-disinfection bacterial tests still showing coliform presence
• Persistent chemical taste or odor after chlorine dissipates
• Suspected agricultural chemical or fuel contamination (shock chlorination does NOT address chemical contaminants)

Prevention Before the Next Storm

• Verify wellhead height. Wellheads must be above the 100-year flood elevation. If yours isn't, have it raised or bermed.
• Maintain the cap seal. A compromised cap allows surface water to enter during normal rain, not just during floods.
• Keep the grout seal intact. The annular space between casing and borehole should be grouted; inspect for subsidence or erosion near the wellhead.
• Baseline test annually. A current "clean" test gives you a reference when a post-storm test comes back suspicious.
• Keep supplies on hand: unscented bleach, bottled water, SCDES hotline number written somewhere other than a phone screen that requires power.

Post-Hurricane Helene Services

Solomon Home Water Solutions serves SC homeowners recovering from Hurricane Helene and preparing for future storms. We provide well inspection, shock chlorination service, coordination with SCDES-approved laboratories for bacteriological testing, and whole-house filtration upgrades for wells with ongoing concerns. Free assessment. Call (843) 890-0511.