1. Store enough water for 24 hours of use.

2. Measure the diameter of the well and calculate the volume of chlorine bleach (5.25% active chlorine- household bleach using Table 1 below).

3. Remove the well cap.

4. Test the pH. Ideally, the pH should be 7 or less. If it is above, add one litre of vinegar or citric acid to the well. Re-test the pH.

5. Mix the bleach in a 5 gallon pail of water. Pour the bleach solution into the well. If the well has a sanitary seal, pour or siphon the bleach solution through the well vent.

6. Run a garden hose into the well to circulate the bleach until the presence of chlorine is detected.

7. Rinse off well cap with chlorinated water and re-fasten to well head.

8. Run water at each individual tap until a strong chlorine odour is detected, including outside and hot water taps.

9. Let the system sit idle for 24 hours. No water should be used during this 24-hour period, except for toilet flushing.

Caution: Bleach solution is strong enough to burn. Keep away from skin, eyes, and children.

10. Open all taps (hot and cold) and let run until chlorine odour can no longer be detected.

11. Wait 24 hours before catching a sample for a bacteria test.

Table 1

Liquid Chlorine (Sodium Hypochlorite)

Required to Produce 50 mg/L of Solution In 100' of Water

Well Disinfection Tips

• Disinfection or sanitization of any well will only kill the bacteria present in the well or on the pumping equipment.

• Every well should be sanitized after construction.

• Each time equipment is removed from a well and re-installed, the well should be sanitized to avoid bacterial contamination.

• The source of bacterial contamination should be identified and removed wherever possible.

• The quantity of chlorine used to sanitize and disinfect a well must produce 50 mg/L (ppm) of chlorine solution when mixed with the total volume of water.

• Faucets on fixtures discharging to a septic tank system should be temporarily diverted to an outside discharge point to avoid having the chlorine solution enter the septic system.

• Bypass carbon filters, RO membranes, and other water treatment equipment that could be damaged if it comes into contact with chlorine. Sanitize these pieces of equipment separately.

• pH adjustment is critical for proper disinfection.

• A residual chlorine of 50 mg/L is necessary for disinfection. Figures given in Table 1 are for 50 mg/L in 100' of water. A solution of 50 mg/L should be sufficient to oxidize any iron or manganese present and sanitize the water system.