You can take action to better prepare your well for a flood, even as you are making plans to evacuate. Store adequate bottled water for drinking and cooking because if your well is submerged even temporarily during a flood event, you won’t be able to drink, brush teeth or cook with the well water until it is tested and found suitable. Complete the following during your evacuation planning:
During Potential Evacuation Preparations
- In South Carolina, our Department of Health and Environmental Control (DHEC) can test your private drinking well water for bacterial contamination. Locate the nearest regional DHEC Environmental Affairs office to obtain sample collection bottles and instructions. If you need help locating the nearest DHEC EA office, your county Extension agent can help you find it.
- If available, locate the log/well report completed when your well was installed and store a copy of it in a safe place that will be accessible if you evacuate.
- Locate contact information for licensed well drillers in the area. If possible, contact a driller/s before evacuating if you think your well will need service immediately after the flood.
- Fill up the pressure tank as much as possible.
- Turn off electricity to the well.
- If you have an aerobic septic system, turn off electricity for the system. No special preparations are recommended for conventional septic systems.
- If you plan to attempt to disinfect your well yourself upon your return, have these basic shock chlorination materials available before the flood because these supplies may be difficult or time-consuming to acquire following a flood:
- Instructions on how to shock chlorinate
- Unscented, household liquid bleach
- Clean five-gallon bucket and five gallons of uncontaminated water
- Garden hose that reaches from an outdoor faucet to the well
- Protective goggles and gloves
- Wrench for well access
- Sample collection bottles from regional DHEC Environmental Affairs office.
- Learn how to bypass water softeners and household water filters if any are attached to your water system. Read and have manufacturer’s instructions easily available on how to disinfect bypassed water softeners and household water filters.
It is strongly recommended that a licensed water well driller be hired to shock chlorinate the well if the wellhead has been flooded or submerged even temporarily. A water well driller will have access to more effective products and will have equipment and experience that a typical well owner will not have. However, if you plan to attempt to disinfect your well yourself, use the following instructions found on this factsheet.
How to Shock Chlorinate a Water Well
If your well system is damaged, the following instructions for the disinfection process will not work. An indication that your well is damaged can be a decrease in water pressure once turned on. Contact a certified contractor for examination.
If your well is contaminated, alternative options include using bottled water, water boiled for at least five minutes or water from a source you know isn’t contaminated.
The water in your well is most likely contaminated after a flood. Ingesting or being exposed to contaminated water may cause sickness. However, these instructions on how to shock chlorinate your well system may solve the issue.
Do not use contaminated water for:
- making ice
- bathing in any form
- washing clothes or dishes
Contaminants could include:
- treatment plant wastewater
- nearby flooded septic system matter
To ensure a safe and effective disinfection process, follow these directions step-by-step:
- A garden hose long enough to reach from an outdoor water faucet to the well
- Protective goggles/gloves
- Clean five-gallon bucket
- Five gallons of water
- Unscented household liquid bleach less than six months old
- How to calculate how much bleach you need:
- The amount of bleach to be used in the disinfection process will depend on the amount of water in the well.
- To calculate the water volume, subtract the static water level (distance from land surface to the water in the well) from the total depth of the well. If you don’t know the static water level, just use the total measurement of the well depth.
- How to calculate how much bleach you need:
Table 1. Amount of unscented household liquid chlorine bleach needed for well disinfection.
|Water depth in well (feet)||
Well diameter (inches)
|10||6 cups||7 cups||8 cups||20 cups||2.5 gal|
|20||7 cups||8 cups||10 cups||2.5 gal||4.5 gal|
|50||8 cups||10 cups||14 cups||5 gal||10.5 gal|
|100||10 cups||16 cups||22 cups|
|150||12 cups||20 cups||30 cups|
|200||14 cups||1.5 gal||2.5 gal|
|400||22 cups||2.5 gal||4.5 gal|
4 cups = 0.25 gal; 8 cups = 0.5 gal; 12 cups = 0.75 gal; 16 cups = 1 gal
STEP BY STEP INSTRUCTIONS
STEP 1 Clear Well of Sediments:
- If you have noticed cloudy or muddy water coming from the well, connect a garden hose to an outside faucet.
- Turn water on at the faucet and let it run until water is clear and free of sediments.
STEP 2 Power Off:
- Turn off electrical power to the pump by turning off the circuit breaker.
- Disconnect water softeners or household water filters by switching to bypass mode or the “out of service” position.
STEP 3 Open the Well:
- Remove all debris near the well. Check the well for damage. Remember, if your well is damaged, this process will not work.
- For a well seal (Figure 1A), remove the threaded well plug for access; for a well cap (Figure 1B) or sanitary cap (Figure 1C), remove the bolts from the cap and lift for access.
- If your well system does not look like the options below, call a contractor for further assistance.
- Fill the five-gallon bucket about three-fourths full with bottled water.
- Look back at Table 1 to determine how much bleach is needed.
- Add bleach to the bucket of water.
- Using the funnel, pour the bleach solution into the thread well plug or well casing.
**** Be careful not to splash/spill the solution
STEP 4 Recirculate the Chlorinated Water:
- Turn on the circuit breaker to the pump.
- Connect the garden hose to an outdoor faucet.
- Next, place the funnel into your well’s access point and put the garden hose into the funnel.
- Turn the water on and let it run for 30 minutes to circulate the bleach within the well.
STEP 5 Running Chlorine Solution Through Faucets:
- Run the chlorinated water throughout the plumbing system. Start inside the house and work your way out by turning on each tap one at a time until you smell bleach.
- Repeat this step for both hot and cold taps, toilet and shower/bath taps and outside faucets.
- Leave the chlorinated water in the plumbing for a minimum of eight hours or overnight.
STEP 6 Flush the Chlorinated Water:
- Run the water through an outside garden hose until you no longer smell chlorine.
- Keep the running water away from your septic system, landscaping and bodies of water.
- Once the chlorine smell is gone from the well, turn on each fixture inside the house one at a time until the chlorine smell in no longer present.
STEP 7 Disinfect Water and Reconnecting Treatments:
- Disinfect home water softener or household filters according to the manufacturer’s instructions and then reconnect those devices.
**** DO NOT DRINK THE WATER UNTIL IT HAS BEEN TESTED. THE WATER SAMPLE IS NOW READY TO BE SENT TO A LAB.
IMPORTANT: Before using the water for drinking, cooking, making ice or preparing food, have the water tested by a SC DHEC certified laboratory. If disinfection attempts fail, the well may need to be cleaned before it is disinfected again. Contact a contractor or local health department for help.
This procedure is based on well disinfection protocols from the SC Department of Health and Environmental Control and Clemson Cooperative Extension, the Florida Department of Health, Minnesota Department of Health, Virginia Tech Cooperation Extension, Texas A&M Agrilife Extension, and Texas Commission on Environmental Quality.