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| How do I disinfect a
bored or dug well? |
Calculate the amount of disinfectant needed by
using the calculation table provided below.
| CHLORINE
BLEACH FOR A BORED OR DUG WELL |
| Diameter of well
(in feet) |
Amount of 5.25%
laundry bleach per foot of water |
Amount of 70%
chlorine granules per foot of water |
| 3 |
1 1/2 cups |
1 ounce |
| 4 |
3 cups |
2 ounces |
| 5 |
4 1/2 cups |
3 ounces |
| 6 |
6 cups |
4 ounces |
| 7 |
9 cups |
6 ounces |
| 8 |
12 cups |
8 ounces |
| 10 |
18 cups |
12 ounces |
- Measure the diameter of the well,
and round the measurement to the nearest foot. (Example: 5.3 feet =
5 feet; 5.7 feet = 6 feet)
- Find the amount of chlorine
bleach needed to disinfect each foot of water for the diameter well
that you have measured. For example, the amount for a 5-foot
diameter well would be 4-1/2 cups per foot.
- Determine the depth of the well
in feet.
- Multiply this measurement by the
computed amount of bleach to use. For a 5 foot diameter, 40 foot
deep well:
- Go to the chart that shows 4-1/2 cups of
chlorine bleach per foot of water for a 5-foot diameter well.
- Next multiply the 4-1/2 cups of chlorine
bleach by the 40-foot depth of the well.
- The total amount of chlorine bleach needed
would be 4-1/2 times 40 or 180 cups of ?chlorine bleach. This is
equal to 11.25 gallons using the conversion of 16 cups in one
gallon.
- Use an appropriately sized, clean
container and pour the measured volume of chlorine bleach into the
well.
- While pouring the chlorine
bleach, try to splash some around the wall or lining of the well.
- Seal the well top.
- Open all faucets and pump the
water until a strong odor of bleach is noticeable at each faucet.
Then stop the pump and allow the solution to remain in the well
overnight.
- The next day, turn on all the
faucets and run the pump until all of the chlorine odor disappears.
Be sure to adjust the flow of the water faucets or fixtures to a
level that avoids overloading the septic system.
- After 5 days of normal usage,
test water for coliform.
| How do I disinfect a
drilled well? |
- Calculate the amount of water in the well by
multiplying the gallons per foot by the depth of the well in feet.
For example, a well with a 6-inch diameter contains 1.5 gallons of
water per foot. If the well is 120 feet deep, multiply 1.5 gallons
per foot by 120 feet to get 180 gallons.
| CHLORINE
BLEACH TO DISINFECT A DRILLED WELL |
| Diameter of well
(in inches) |
Gallons (per
foot) |
| 3 |
0.37
|
| 4 |
0.65 |
| 5 |
1.0 |
| 6 |
1.5 |
| 8 |
2.6 |
| 10 |
4.1 |
| 12 |
6.0 |
- For each 100 gallons of water in
the well, use the amount of chlorine bleach (liquid or granules)
indicated in the table below.
AMOUNT
OF DISINFECTANT REQUIRED
FOR EACH 100 GALLONS OF WATER |
| Chemical |
Amount |
| Laundry bleach (5.25%
Chlorine) |
3 cups (*) |
| Hypochloride Granules
(70% Chlorine) |
2 ounces (**) |
(*)
1 cup = 8 ounce measuring cup
(**) 1 ounce = 2 heaping tablespoons of granules |
- Mix the total amount of liquid or
granules with about 10 gallons of water.
- Remove the access nut on the well
casing top.
- Use a funnel and pour the
solution into the top of the well.
- Connect a hose to a faucet on the
discharge side of the pressure tank and insert it into the well
casing top.
- Start the pump. Spray the water
back into the well and wash the sides of the casing for at least 15
minutes.
- Open every faucet in the system
and let the water run until the smell of chlorine can be detected.
- Close all the faucets and seal
the top of the well.
- Let the chlorinated water stand
in the system several hours, preferably overnight.
- After letting the water stand,
turn on the pump and open all faucets. Let the water run until all
odor of chlorine disappears. Be sure to adjust the flow of water
from faucets of fixtures that discharge into septic tank systems to
a low flow to avoid overloading the drain field.
- After 5 days of normal usage,
test water for coliform.
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