WELL DISINFECTION PROCEDURE

Problems of sulfate reducing bacteria, iron bacteria, and organic tastes and odors can often be eliminated by a complete chlorination of the well and distribution piping.

The procedure for chlorination of a well follows.   You will need:

• Liquid bleach (standard household bleach, such as Clorox, unscented).  The correct quantity is 1.5 quarts for every 100’ of water in a drilled well.  If you do not know the depth of the well, start with one half gallon of bleach.
• Garden hose
• OTO, which is a pool chlorine detection chemical available from a pool supply store or Secondwind.  This is not mandatory, but helps.

1.  Put any water treatment equipment on bypass. Remove any cartridges from filter housings.

2.  Open the cap of the well. Pour the liquid bleach into the well.

3.  Run water from a garden hose into the well. Leave the hose pointed into the well. Let the hose run until chlorine is detected in the water stream. You detect the chlorine by filling a white cup with the water and dropping a few drops of OTO into the cup. If the drops turn yellow or orange, you have chlorine. (If you do not have OTO you will have to rely on your nose.) This will take from 30 minutes to an hour depending upon the amount of water in the well.  If you do not have chlorine present after an hour, add more bleach, approximately one quart at a time.  Keep running the water for approximately 15 minutes each time after adding more bleach to see if you now have enough, before then adding more. 

4.  When you have chlorine at the hose, rinse the inside walls of the well with the hose for a few minutes. Then turn off the hose, reattach the cap of the well. NOTE that if you have iron in the water, the water will become yellow or rusty colored during this time. Disinfecting a well can also stir up sediment, so be prepared that aerators may become plugged.

IN THE HOUSE

5.  Run water at each faucet, testing for chlorine presence.  Turn off each faucet once chlorine is present. For complete disinfection, run some water into the dishwasher and washing machine and flush all toilets. If you have a tank-type hot water system, it will take a while to get chlorine through the hot water.

6.  Allow the chlorine to sit in the plumbing at least 24 hours. You may flush the toilet during this time, but do not shower in the water or use it for cooking or drinking. It is a good idea to run each faucet a little bit a few times each day to keep the chlorine fresh.

AFTER 24 HOURS

7.  Flush the well by pointing your garden hose to the woods or a gravel or sandy area. Run the hose until the chlorine is gone. During this time you should stay around and check on the water stream every now and then to make sure you don’t temporarily run the level of water in the well down below the pump. Should the water stream drop down to a trickle, turn off the hose for a few hours.

8.  If you wish to disinfect your water filter or softener, wait until the chlorine strength has dropped to a slightly detectable level. Put your system back on line and run water through until you detect chlorine at the kitchen sink. If you have a Kinetico, be sure to run some water through both sides by moving the black dot on the top of the valve, and running water again at the sink. After you have done this, put the systems back on bypass until the disinfection flushing is complete. (This will prevent systems from becoming fouled due to a higher than normal level of sediment.)

9.  When the chlorine is gone and any turbidity stirred up by the process has dissipated, you may put your water treatment equipment back on line, and replace any cartridges.