How to disinfect your water system
If your analytical results for Total Coliform/E.coli are PRESENT or greater than 1, you may need to disinfect your well. This is a process that you can do yourself, or you can consult a well driller or water treatment specialist the help you.
- Take a look at the water system itself. Make sure it is constructed properly. Dug wells and springs should be of concrete construction with a tight cover. Drilled wells should extend up above the ground and have a good cap. They should not be buried or in a pit.
- Look at the location. A water supply should not be in a wet or soggy area. It should be isolated from nearby septic systems.
- When the first and second items are determined to be okay, the system should be disinfected with chlorine.
Liquid bleach should be used for springs and dug wells. Use the chart below to determine the appropriate amount. Ten feet of water in a 36 inch diameter well would require 1 gallon of bleach (figure accordingly). Mix the chlorine thoroughly, recirculating it to the well for several hours through a garden hose hooked up to an outside faucet. Turn on each faucet in the house and run the water until the chlorine odor is detected. Then turn off the faucet. This process will ensure that all the lines in the plumbing system are exposed to the chlorine. Let the chlorinated water sit overnight in the well and plumbing. Then let the water flush through the system. DO NOT sample again until at least 48 hours after the odor of chlorine has disappeared. You may need to disinfection the system more than once to eliminate all of the bacterial contamination.
Watch the video below from Vermont Rural Water Association to see this process in action.
| Gallons of Bleach for 6″ Diameter well | Depth of Standing Water in Feet |
| .84 | 60 |
| .98 | 70 |
| 1.0 | 75 |
| 1.1 | 80 |
| 1.2 | 85 |
| 1.3 | 90 |
| 1.4 | 100 |
| 1.5 | 110 |
| 1.7 | 120 |
| 1.8 | 130 |
| 2.0 | 140 |
| 2.1 | 150 |
| 2.25 | 160 |
| 2.5 | 175 |
| 2.8 | 200 |
| 3.2 | 225 |
| 5 Gallons | 380 |
