Hurricane Well Decontamination in Central Florida: What to Do After Flooding

After a hurricane floods a Central Florida private well, the well water is presumed contaminated until proven otherwise by laboratory testing. The decontamination process has four steps: wait for floodwaters to completely recede, inspect the wellhead and casing for physical damage, perform shock chlorination using unscented household bleach to achieve 50 to 200 milligrams per liter of free chlorine in the water column, and then flush and test using a Florida-certified laboratory before resuming use. The Florida Department of Health recommends bottled water for drinking and cooking throughout this process. Chlorine concentration figures used in shock chlorination come from CDC and EPA shock chlorination guidance, not from a contractor's estimate. The timeline from a flooded well to a confirmed-safe test result is typically three to five days under good conditions. Call a licensed well contractor if the casing was physically damaged, if the pump failed, or if post-chlorination testing still shows bacteria.

How Long Should You Wait Before Touching Your Well After a Hurricane?

The first rule after a hurricane in Central Florida: do not open the well cap, attempt to run the pump, or try to use the water until floodwaters have fully receded from around the wellhead. Running a pump submerged in floodwater forces contaminated surface water directly into the distribution lines and appliances, extending the decontamination scope well beyond the well itself.

Once the area around the wellhead is dry:

• Inspect the wellhead. Look for debris, mud, or standing water inside the well cap. A bent or dislodged well cap is a sign that contaminated water entered the casing directly. Note the condition before proceeding.
• Do not run the pump to “clear” the water before disinfection. Running the pump distributes whatever is in the well through the entire plumbing system.
• Switch to bottled water for all drinking, cooking, and teeth brushing immediately after the storm, regardless of whether the well appears visually normal. Visual clarity tells you nothing about bacterial contamination.

The Florida Department of Health's private well guidance (floridahealth.gov) is the authoritative source for current post-storm well protocols in Florida. The steps in this guide align with DOH recommendations and the EPA emergency disinfection guidance at epa.gov, but always verify with the current official guidance because protocols can be updated after major storms.

What Contaminants Enter a Florida Well After Hurricane Flooding

Central Florida hurricane flooding introduces a different contamination profile than a routine heavy rain event. The primary concerns:

• Fecal coliform bacteria and E. coli. Floodwater in Florida carries bacteria from overwhelmed septic systems, livestock, wildlife, and stormwater runoff. These are the primary indicators tested after any well flooding event. A positive E. coli result means the well water is contaminated with fecal material.
• Other pathogens. Floodwater can carry Giardia, Cryptosporidium, and occasionally hepatitis A virus. Shock chlorination at adequate concentration and contact time is effective against bacteria; Cryptosporidium is chlorine-resistant and may require UV disinfection or boiling for additional protection in heavily contaminated wells.
• Sediment and turbidity. Fine silt and suspended solids from floodwater reduce the effectiveness of chlorination by shielding bacteria from the disinfectant. High turbidity after flooding is a sign that more aggressive cleaning is needed before chlorination. For wells that develop sediment problems after storm damage, see our guide on sandy or gritty well water in Central Florida.
• Nitrates and agricultural chemicals. In farming areas of Central Florida (Polk, Lake, and Hendry counties in particular), hurricane flooding can carry fertilizer runoff and agricultural chemicals into well water. If your well is near cultivated land, include a nitrate panel in your post-storm test. See the well water filtration guide for treatment options.
• Fuel and chemical spills. Floodwaters often carry hydrocarbons from flooded vehicles, storage tanks, and industrial areas. If there is any possibility of fuel or chemical contamination in the floodwater, standard shock chlorination is not sufficient. Call a licensed contractor and potentially a certified environmental lab for extended testing.

The Floridan Aquifer, which most Central Florida drinking water wells draw from, is generally well-protected by the confining layers above it. Contamination from a surface flood event typically enters through the well casing itself, either through a damaged well cap, a cracked or corroded casing, or through the annular space around the casing if grouting has failed over time. See our Central Florida well drilling guide for context on aquifer geology and well construction.

What Chemicals Are Used to Shock a Well and What Concentrations Are Safe

Shock chlorination uses household bleach (sodium hypochlorite solution) to raise the free chlorine concentration in the well water column high enough to kill bacteria, viruses, and other pathogens. The CDC shock chlorination guide at cdc.gov and the EPA emergency well disinfection guidance at epa.gov are the authoritative sources for chlorine dosage. The figures below come from those sources.

Bleach type to use

Use unscented liquid household bleach that lists sodium hypochlorite at 5.25 to 8.25 percent as the active ingredient. Do not use scented bleach, color-safe bleach, gel bleach, or any product with added cleaners or surfactants. The label should say “EPA registered” for use as a disinfectant.

Target chlorine concentration

Per CDC and EPA guidance, the target free chlorine concentration for shock chlorination of a flooded well is:

• 50 mg/L (ppm) for routine well disinfection after bacterial contamination without surface flooding.
• 200 mg/L (ppm) for wells that have been flooded by surface water during a hurricane or major storm event, as recommended in EPA emergency disinfection guidance. The higher concentration accounts for the heavier contamination load and the organic matter that may shield pathogens from the disinfectant.

Verify these concentrations against the current CDC and EPA guidance before beginning, as recommendations can be updated.

Calculating bleach volume for your well

The volume of bleach needed depends on your well diameter and the height of the water column inside the well. The CDC shock chlorination guide includes a table by well diameter and depth that gives exact bleach volumes in quarts and gallons for standard bleach concentrations. Use that table, not a rule-of-thumb estimate.

As a general reference from the CDC table, for a 4-inch-diameter well with 8.25 percent bleach, achieving 200 ppm requires approximately 2 to 3 pints of bleach per 100 feet of water column. For 6-inch wells, the volume roughly doubles per 100 feet. Verify your exact calculation using the CDC table at cdc.gov/healthywater.

Step-by-Step: How to Disinfect a Well After Hurricane Flooding in Florida

This procedure follows CDC and EPA shock chlorination protocols adapted for Florida post-hurricane conditions. Read all steps before starting. If the well casing is physically damaged or the pump is not operational, stop and call a licensed well contractor before proceeding.

1. Wait for floodwaters to recede completely. The area around the wellhead must be dry and the floodwater must be gone before you begin. Do not rush this step.
2. Remove debris from around and inside the well cap. Carefully remove the well cap. Clear any mud, leaves, or debris from the cap seal area. If debris has entered the well casing, note it but do not try to remove it yourself; that requires a contractor with a camera and bailing equipment.
3. Calculate your bleach volume using the CDC shock chlorination table based on your well diameter (typically 4 or 6 inches for Central Florida residential wells) and the static water level depth. Most residential wells in the Floridan Aquifer in Central Florida have static water levels 20 to 80 feet below the surface.
4. Pour the measured bleach into the well. Use a clean funnel or pour directly into the casing. Avoid splashing bleach on your skin or eyes; wear gloves and eye protection. After pouring, replace the well cap loosely to allow gas to escape while the chlorine works.
5. Circulate the chlorine solution. If the pump is operational, run water through an outdoor spigot until you smell chlorine at the tap, then connect a hose and run water back into the well to circulate the bleach throughout the casing. Continue until the water coming out of the tap smells strongly of chlorine. Then open every indoor tap until you smell chlorine, and let it contact the plumbing.
6. Allow contact time. Shut everything off and let the chlorinated water sit in the well and distribution lines for at least 12 hours, and preferably 24 hours. Do not use any water during this period.
7. Flush the system thoroughly. After the contact period, run water from outdoor spigots (away from septic drain fields and plants, since the highly chlorinated water harms them) until the chlorine smell is gone. Then flush indoor taps progressively. This may take one to two hours of continuous pumping on a residential system.
8. Collect a water sample for lab testing. After flushing, collect a water sample using a sterile collection bottle from a Florida-certified lab. Do not collect from a filter tap; collect from a cold water tap that goes directly from the line. Follow the lab's instructions precisely, including whether to flush the tap before collecting or collect first-draw water.
9. Continue using bottled water until results are in. Do not resume use of well water for drinking or cooking until you have a laboratory report showing the water is free of total coliform and E. coli. If the test comes back positive, repeat the shock chlorination process and retest before using the water.

If you repeat the process twice and the well still tests positive for bacteria, the well likely has a structural problem (a cracked casing, failed grout seal, or compromised well cap) that allows surface water to continue entering. At that point, a licensed Florida well contractor needs to camera the well and assess whether rehabilitation or replacement is required. For pump problems that appear after the storm, see our well pump troubleshooting guide and pump repair page.

How to Test Your Well Water After a Hurricane in Florida

Post-hurricane well testing must be done by a Florida-certified laboratory, not a home test kit. The standard post-flood panel:

For wells near industrial sites, fuel storage, or areas with known chemical hazards in the floodwater, also request testing for petroleum hydrocarbons and any site-specific chemicals.

The Florida Department of Health certified laboratory list is at floridahealth.gov/environmental-health/drinking-water/lab-certification. Most Central Florida labs offer 24 to 48-hour turnaround on bacteria panels. Call ahead after a hurricane, since labs are often overwhelmed with post-storm samples and turnaround times can extend. For the full picture on well water testing in Florida, see our Florida well water testing guide.

When to Call a Professional Instead of Doing It Yourself

Shock chlorination is a task most homeowners can do themselves following the CDC and EPA guidance. However, there are situations where a DIY approach is not sufficient and a licensed Florida well contractor is required:

• Physical damage to the well casing or cap. A bent or cracked casing, a dislodged well cap, or visible damage to the wellhead requires a contractor to assess whether the well can be rehabilitated or needs to be replaced. Shock chlorination alone does not fix structural failures.
• Mud or debris inside the well casing. If the well casing was completely submerged and mud entered, the well needs to be bailed, cameras-inspected, and possibly developed by a contractor before shock chlorination can be effective. You cannot adequately chlorinate a silted-up well.
• Pump failure. If the pump is not running, is making grinding or clicking sounds, or is producing no water after the storm, do not attempt chlorination until the pump has been assessed. A pump that was running while submerged may have failed or may have drawn contaminated water into the lines. See the well pump troubleshooting guide and our pump repair service page.
• Repeated positive test results after two rounds of chlorination. Two failed chlorination attempts indicate a continuing pathway for contamination to enter the well. A licensed contractor needs to camera the well and identify the entry point before further chlorination attempts.
• Well older than 20 years with unknown casing condition. Older wells in Central Florida may have corroded steel casings or degraded grouting that provides minimal protection during a flood event. If you do not know your well's construction history, have a contractor inspect it before assuming shock chlorination is sufficient.
• Fuel or chemical contamination in the floodwater. Shock chlorination does not remove petroleum hydrocarbons or most industrial chemicals. If the floodwater was visibly oily or there is any indication of a fuel spill in the area, call a contractor and potentially an environmental consultant before attempting standard disinfection.

Quality Filters And Pumps provides post-hurricane well inspections, pump assessments, camera inspections, and well rehabilitation across Central Florida. FL Water Well Contractor License #7494. We serve Orlando and Orange County, Kissimmee and Osceola County, Lakeland and Polk County, Ocala and Marion County, Sanford and Seminole County, and Gainesville and Alachua County.

Protecting Your Water Treatment System After the Storm

Hurricane floodwater does not only affect the well. If any component of your water treatment system was submerged, it needs evaluation before being put back into service.

Water softeners and iron filters

Softener tanks and iron filter tanks are typically sealed, but their control valves, brine tanks, and media beds can be affected by flooding. If the control valve was submerged, the electronics may have been damaged. The resin or filter media inside a flooded tank should be tested or replaced before relying on it to treat water that is being used for drinking. See our water softener installation guide for how these systems work, and contact us if you need a post-storm inspection of existing equipment.

Reverse osmosis systems

Point-of-use RO systems under the sink can be submerged during significant flooding. A flooded RO system should be disinfected and have its filters and membrane replaced before returning to service. RO membranes that have been contaminated with floodwater should be treated as compromised regardless of their replacement schedule. See the RO system repair guide for maintenance and replacement details.

Appliance damage from untreated well water after a storm

Running a well pump into a distribution system that circulates contaminated water can also deposit sediment and biological material inside water heaters, washing machine hoses, and dishwasher inlets. After completing the decontamination and receiving a clean test result, flush water heaters by opening the drain valve until the water runs clear. For the longer-term picture on how well water affects appliances, see our guide on how hard water damages appliances.

PFAS and hurricane flooding

Floodwater from military base areas or industrial zones in Central Florida can introduce PFAS to a well that was previously PFAS-free. Standard shock chlorination does not remove PFAS. If your well is near a known PFAS source area and was flooded during a hurricane, include PFAS testing in your post-storm water analysis. See our guide on PFAS in Central Florida private wells for testing and treatment options.

Preparing Your Well Before Hurricane Season

The best time to assess well vulnerability is before hurricane season, not after the storm. Pre-season steps that reduce post-hurricane decontamination risk:

• Inspect and replace the well cap. The well cap is the primary barrier between the surface environment and the well water. Caps should be sanitary-type caps with a gasket seal. If your cap is cracked, corroded, or does not seal tightly, replace it before storm season. A good cap costs a fraction of a post-storm decontamination.
• Check the grout seal around the casing. The grout that seals the annular space between the well casing and the borehole is what prevents surface water from running down alongside the casing and directly into the aquifer. If the grout has cracked or sunk (visible as a gap around the casing at grade), have it restored.
• Raise the wellhead above the flood elevation for your area. If your well is in a low-lying area that has flooded before, extending the casing above the typical flood elevation and raising the electrical conduit entry point reduces the risk of future flooding events contaminating the well.
• Have a current water test on file. A baseline water test from before the storm is valuable for comparison after it. Without a baseline, you cannot know which post-storm results reflect new contamination versus pre-existing water quality conditions.
• Stock chlorination supplies. Keep a sealed gallon of unscented 8.25 percent bleach in a cool, dark place along with a clean funnel and the CDC shock chlorination dosage table printed and stored with your emergency supplies. Fresh bleach is more effective than old bleach; the sodium hypochlorite concentration degrades over time.

For information on well installation and construction standards that affect hurricane resilience, see our Central Florida well drilling guide and our well drilling service page. For financing options for well rehabilitation or new well installation, see our financing page.

Well Water Filtration Series: Related Guides

This guide is part of the Central Florida well water filtration hub. The full series covers every major contaminant and treatment topic for Floridan Aquifer well owners:

• Well Water Filtration: A Complete Treatment Guide (pillar) covers contaminants, treatment sequencing, and system sizing logic for Central Florida wells.
• Iron and Sulfur Treatment Near Ocala covers air-injection oxidation and catalytic media for the iron and hydrogen sulfide common in Marion County.
• PFAS in Central Florida Private Wells covers the 2024 EPA rule, where PFAS occur in Central Florida, and what treatment options remove them.
• RO System Repair and Service covers membrane replacement, pre-filter service, and post-storm RO system restoration.
• Sandy or Gritty Well Water covers the four root causes and corresponding fixes for sediment in Central Florida wells.
• Water Softener Installation in Central Florida covers hardness treatment sizing for Floridan Aquifer water.
• How Hard Water Damages Appliances covers the measurable impact of untreated Floridan Aquifer water on water heaters, washing machines, and RO membranes.

Additional guides: see well pump troubleshooting, well pump repair, and Central Florida well drilling. Service pages: well drilling, water filtration, pump repair. About Chase Norris and the company: about us.

Frequently Asked Questions About Hurricane Well Decontamination