Disinfection of Wells
The following methods are recommended for the disinfection of wells and springs that have been flooded or accidentally polluted:
- Disinfection should be done only after the flood waters have receded.
- In the meantime BOIL THE WATER BEFORE DRINKING.
How To Disinfect the Well Water
- Treat water with any of the 5% household bleaching solutions obtainable from the local grocery store Javex , Chlorox and Perfex are examples.
- Pour into the well a quantity of the bleaching solution as indicated in the table below, start the pump and open all taps. If it is a dug well without a pump, the chlorine solution should be allowed to mix thoroughly in the well and then let stand for at least 24 hours.
- When a chlorine odor is detected at the taps, close each tap and stop the pump.
- Open the valve or plug at the top of the pressure tank, just before the pump is stopped, to allow the chlorine solution to come into contact with the entire inside surface of the tank. This valve or plug should then be closed.
- WHETHER IT IS A DUG WELL OR ONE EQUIPPED WITH A PUMP, THE CHLORINATED WATER SHOULD REMAIN IN THE SYSTEM OVERNIGHT TO 24 HOURS.
TABLE OF QUANTITIES OF 5% HOUSEHOLD BLEACHING SOLUTION REQUIRED FOR DISINFECTION OF WELLS
| Diameter of Well, Spring or Pipe IN INCHES | Amount of Household Bleach Required for each 10 foot depth of water in the Well, Spring or Pipe.* | ||
|---|---|---|---|
| 2 | 1 tsp | = | 5 mL |
| 4 | 4 tsp | = | 20 mL |
| 6 | 10 tsp | = | 50 mL |
| 8 | 7 tbsp | = | 105 mL |
| 10 | 10 tbsp | = | 150 mL |
| 12 | 13 tbsp | = | 195 mL |
| 24 | 3 ½ cups | = | 875 mL |
| 36 | 2 qts | = | 2.2 L |
| 48 | 3 qts | = | 3.3 L |
| 60 | 5 qts | = | 5.5 L |
| 72 | 7 qts | = | 7.7 L |
| 96 | 3 gals | = | 13.5 L |
Further information and advice in connection with the disinfection of your well or water system may be obtained from your local health unit office.
- ** PLEASE NOTE:
1) Excess of the recommended bleach may poison your septic field.
2) A Total & Fecal Coliform test should be repeated 7-14 days after bleach treatment.