Follow these directions for
disinfecting your well if your water has coliform bacteria in it. This
disinfection process treats only biological contaminants, not chemical or
mineral contaminants. Disinfecting Your Well
Flush the System.
- If your water is cloudy, let
the water run for 10-15 minutes before disinfecting.
- Use household bleach which
typically has a chlorine concentration of 6%. Do not use “ultra” concentrated
bleach or bleach products with additives or
- The amount of bleach to use
is according to the chart on page 2. If you have problems calculating the
amount of bleach to use, contact Thurston County Environmental Health.
- Mix bleach in a bucket of
water. Remove well cap, plug, or vent (see diagrams on page 2); using a funnel,
pour the bleach into your well.
the bleach with the well water.
- Attach a hose to the nearest
outside faucet and allow the water to run onto the ground for 1-2 minutes until
you smell chlorine. Then place the hose in the hole where you poured the
bleach, allow the water to run back into the well for 15-20 minutes.
- Remove the hose and replace
the well cap, plug, or vent.
Chlorinate the lines.
- Turn on each tap attached to the well (kitchen, bathroom, outdoor spigot,
etc.), starting with the nearest tap to the well, and let the water run until
you smell bleach, turn off and then go to the next tap.
- Turn off electricity to the
pump and let sit overnight.
Flush the chlorinated water out of the system.
Choose any outdoor spigot and let the water run onto the ground, away from your septic system (also keep water flow from going into creeks, streams, or where fish or vegetation can be harmed), until you no longer smell bleach. This empties the bleach from the well.
Turn on each faucet inside the house until you no longer smell bleach.
Once the system has been flushed
of all bleach, the water can be used for laundry and bathing but you should not yet use it for drinking, brushing
teeth, making ice or preparing food.
Wait 3-4 days
after flushing the bleach out to collect coliform bacteria samples. You may need to repeat
this process several times before coliform test results are “satisfactory”.
Also, be aware that the bleach may disturb built-up minerals in your pipes and
temporarily discolor your water. This discoloration should disappear once the
bleach is flushed out of your system.
For more information, call
Thurston County Environmental Health Division at (360) 867-2673.