Sometimes it becomes necessary to disinfect your well and distribution system following an unsafe sample, recent plumbing work, flooding event or other potential contamination discoveries. Not everyone wants to pay a well driller to come out and provide this service, however, it is recommended that you do.

There are a few ways you can get this done:

THE GOOD WAY for most 4"-5" diameter wells.
THE BETTER WAY for calculating proper concentrations for all well sizes.
THE BEST WAY by hiring a professional.

THE GOOD WAY is generally a decent quick and easy method for 4"-5" well casings without consideration to concentration, well depth or static water table.

If the water is discolored, flush the water through a garden hose until the water flows clear.

Locate a clean 5 gallon pail, 1 quart of new, unscented household bleach and water. Empty the entire contents of bleach from the bottle into the 5 gallon pail. Fill the bucket to the top to make the chlorine solution. Remove the well cap and carefully move the wiring bundle to one side.

Pour the 5 gallons of disinfected water down the well casing trying to get all of the casing wall soaked. Run a garden hose inside the well and rinse down the casing and internal parts for 10-15 minutes.

Reassemble the well cap and wiring.

Bypass any water conditioning devices at this time. Shut off all fixtures. Run every fixture one at a time until you smell the bleach solution at each fixture. Allow the bleach to remain in the distribution system for a minimum of 6 hours before flushing. (Overnight if possible)

Connect a hose(s) to a fixture or fixtures and run the water away from the septic system, final disposal, well, home foundation or any other areas to preclude flooding. Run the water until all traces of bleach are absent which may take from several hours to a few days. Do not run inside plumbing to flush the well because this can overburden or damage your septic system.

After the system has been completely flushed the water conditioning device or devices can be taken off bypass. Briefly flush any residual bleach from water conditioning equipment (approximately 5-10 minutes) before sampling.

Sampling should be conducted within 2-3 days following this procedure.


Follow the procedures as indicated in THE GOOD WAY with the exception of the 1 quart bleach to 5 gallons of water concentration. (See chart below for proper bleach concentration)


Well Depth


2 inch well 4 inch well 5 inch well 6 inch well 8 inch well
20 feet 8 ounce 8 ounce 8 ounce 16 ounce 32 ounce
30 feet 8 ounce 8 ounce 16 ounce 16 ounce 32 ounce
40 feet 8 ounce 8 ounce 16 ounce 16 ounce 32 ounce
50 feet 8 ounce 16 ounce 16 ounce 32 ounce 64 ounce
80 feet 8 ounce 16 ounce 32 ounce 48 ounce 64 ounce
100 feet 16 ounce 24 ounce 32 ounce 48 ounce 80 ounce
150 feet 16 ounce 32 ounce 48 ounce 64 ounce 96 ounce
200 feet 16 ounce 48 ounce 48 ounce 64 ounce 96 ounce



The BEST way to properly disinfect your well and distribution system is to contact a registered well driller.