Shock chlorinate & sanitize your well & home piping system whenever:
·
A new well has been constructed
·
Anytime a well is opened for repairs
·
Flood water has entered a well
·
A new holding tank, pump or pressure tank has been installed
·
A new pipeline or other piping or plumbing work has been done
·
Tests indicate the presence of coliform bacteria
·
Odors or slime caused by iron or sulfur bacteria are present
Shock Chlorinate & Sanitize Wells with Chlorine to Kill Bacteria
It is important to
periodically monitor your well to see if contamination is present. The United States Environmental Protection Agency recommends that private water
supplies are tested annually for coliform bacteria to detect contamination
problems early.
A positive test for
coliform bacteria in a well or home piping system indicates that
disease-causing bacteria and viruses are likely to be present.
This can mean that the
well is under the influence of surface water, septic tanks leaking into the
well, or that the well was not properly disinfected after either being drilled
or serviced.
Other bacteria such as
iron and sulfur bacteria, while not a health threat, can produce obnoxious
odors, tastes, and color, and can cause plugging problems in pump and water
systems.
Shock chlorination can
eliminate the disease-causing bacteria and other nuisance organisms that cause
tastes, odors, and slime.
Coliform bacteria
tests are used as an indicator of the possible presence of disease-causing
bacteria.
You can test for
bacteria yourself using a Home Coliform Bacteria test kit, or get a
sterile bottle and take it to a lab for a certified test. You can often find
a licensed laboratory in your area.
CAUTION: While the shock
chlorination may correct bacteria and/or odor problems in wells and piping
systems in the short term, it does not correct the source of the bacterial
contamination.
If bacteria are
entering the well from a septic tank or other source, the bacteria will become
present again after the well has been sanitized.
Try to identify or
trace the source of the bacteria and protect the well itself from
contamination.
CAUTION: Shock
chlorinating your well may cause the water to turn a dark color and the
chlorine may clean the well shaft and pipe of iron and sediment.
The water may
initially be very high in sludge and rust and cause damage to pipes and
fixtures.
Do not run water high
in rust and sediment into water softeners, interior fixtures, water heaters, etc.
Which Type of Bleach to Use
The best way to shock
chlorinate a well is to use a combination of dry pellets and dry chlorine
granules mixed with water. The dry pellets drop down past the pump and
ensure the entire well is sanitized. In addition, liquid bleach made from
potable water grade powdered bleach is poured into the well and then
recirculated until the chlorinated water has made its way through the well
pipe, pressure tank, and pipes in the house if desired.
You can use regular
household bleach (non-perfumed type) that contains 5.25 percent sodium
hypochlorite, which kills bacteria and certain viruses. Laundry bleach can
contain contaminants such as benzene and heavy metals so only use as a last
resort if you cannot find the powdered bleach and pellets.
You can also use pool
chlorine, which is 10% to 12% sodium hypochlorite and twice as strong as
household bleach. Do not use pool pellets, which are not designed for potable
water.
Note of Caution:
Shock chlorination of wells or piping systems may loosen up the scale, iron deposits and other materials, which can clog fixtures, appliances, and valves in the piping system. Care should be taken when flushing the piping, and all aerators removed to prevent clogging. In some extreme cases of corroded piping, the piping may fail and start to leak after this procedure. Chlorination will not remove nitrate or other contaminants.
Shock chlorination of wells or piping systems may loosen up the scale, iron deposits and other materials, which can clog fixtures, appliances, and valves in the piping system. Care should be taken when flushing the piping, and all aerators removed to prevent clogging. In some extreme cases of corroded piping, the piping may fail and start to leak after this procedure. Chlorination will not remove nitrate or other contaminants.
Shock Chlorination Using Dry Pellets or Powdered Bleach
The dry pellet method
(70% calcium hypochlorite) can be used for well, storage tank, or cistern
sanitation. The number of tablets and granules used will depend on the amount
of water in the system to be sanitized. Half of the total treatment will be
completed with chlorine pellets and the other half will be completed with
granular chlorine slurry.
A 100-ppm chlorine
concentration is ideal for sanitizing a well. To produce a 100
PPM chlorine concentration, use 2 oz. sanitizer pellets or granules for
every 100 gallons of water in the system. (2oz. granules = 70 Pellets) If the
water has a high iron or sulfur content more chlorine may be needed to achieve
100-ppm chlorine residual.
Instructions
1. Bypass the water
softener, other filters, or purification equipment. Clean the well house,
spring house or storage tank or reservoir. Remove debris and scrub or hose off
any dirt or other deposits or interior surfaces. Pump to remove any suspended
solids or foreign matter in the water if possible. Scrub interior surfaces of
well house with a strong chlorine solution containing ½ gallon household bleach
or 0.2 oz of dry bleach granules to every 5 gallons of water.
2. Remove the small
well inspection plug on top of the well. For some wells, particularly for wells
completed with pitiless adapters or buried pressure tanks, there may be a
rounded cap that has no inspection hole. Remove the cap or seal from the casing
and, if possible, measure the depth of water in the well, then refer to the
table below to determine how much sanitizer should be used. You can
also estimate well and water depth from well logs or other records.
CAUTION: well caps and
seals are integral to the safety and integrity of your well. They are often
regulated by the state and local codes. Be certain to comply with all
applicable codes and licensing laws, whenever opening a well. If you are unsure
of any of the following steps, seek the assistance of a qualified or licensed
well driller or pump installer or contractor.
Well Casing Diameter
|
Gallons of Water Per 100 Feet
|
Oz. of Granules to Achieve 100 PPM
|
Number of Pellets to Achieve 100
PPM
|
4″
|
70
|
1.3
|
49
|
6″
|
150
|
2.9
|
106
|
8″– 12″
|
260
|
5.1
|
183
|
12″ – 16″
|
590
|
11.6
|
415
|
20″ – 24″
|
2350
|
46.0
|
1654
|
30″ – 36″
|
5290
|
104.0
|
3724
|
4. Mix the determined
amount of granules needed in a clean, plastic five (5) gallon container of
water and pour the solution down the well to sanitize the upper portion of the
well. Do not add water to the product – Add product to water.3. Drop one tablet into
the well and listen to hear if the tablet hits the water (you will hear a
“plink” sound). If the tablet hits the water, drop the remaining determined a number of sanitizing tablets needed into the well.
5. It is necessary to
circulate the water in the well to mix the sanitizer thoroughly throughout the
entire water system. Connect a hose to an outside sillcock (also known as a
hose bib) that is located after the pressure tank and run water back down the
well (this also rinses the upper portion of well).
After approximately 15
minutes of circulating the water, a strong chlorine odor should be present; if
not, repeat steps 4 and 5. Run water through service lines until you detect
chlorine odor at all taps.
6. Allow the sanitized
water to stand in the system for at least six (6) hours, although overnight is
preferred. Open an outside faucet and flush system until water runs chlorine-free (no chlorine smell is detected). Repeat flush operation on each faucet in
the system.
Do not run high levels
of chlorine down the drain into the septic system.
Note:
A) Chlorine may make the water run colored, and iron deposits, slime, and organic material may break loose and plug pump screens.
A) Chlorine may make the water run colored, and iron deposits, slime, and organic material may break loose and plug pump screens.
***DO NOT CONTINUE TO
RUN PUMP IF WATER DOES NOT FLOW. ***
B) The high level of
chlorine required to sanitize a water system is corrosive to most metals and
the chlorine solution must not remain in the water system more than thirty-six
(36) hours before completely flushing from the system.
7. Return all
equipment to the service position.
8. After the chlorine
has been left in the well (and the plumbing system if applicable) for a minimum
of 6, up to 12 hours, the chlorinated water can be discharged. Large amounts of
chlorinated water should not be discharged into the septic tank, or onto lawns
or gardens.
9. If possible,
discharge as much of the water as possible through an outside faucet with a
hose attachment. Do not discharge the chlorinated water into streams or rivers.
The small amount of chlorinated water, which remains in the household plumbing,
can be discharged into the septic system.
The water should be
tested 2 to 3 weeks after sanitizing. If bacteria, iron bacteria, sulfur, or
other problems recur, contact your water professional for further treatment.
Shock Chlorination Using Liquid Chlorine Bleach:
1. Clean the well
house, spring house or storage tank or reservoir.
2. Remove debris and
scrub or hose off any dirt or other deposits or interior surfaces.
3. Pump to remove any
suspended solids or foreign matter in the water if possible. Scrub interior surfaces
with a strong chlorine solution containing ½ gallon household bleach to each 5
gallons of water.
4. Determine how much
chlorine to use to disinfect your well by consulting Table 1. If you don’t know
your well depth, contact your well driller as they often keep records that will
show the depth of the well.
See chart below to
find out the amount of 5% chlorine bleach (sodium hypochlorite) needed for
disinfection to obtain approximately a 100 ppm chlorine solution in the
well.
If using pool chlorine
(10% to 12% sodium hypochlorite) use half as much chlorine bleach.
Well Casing Diameter
|
Distance From Water Level to
Bottom of Well (Water Depth)
|
|||||
0′ – 50′
|
50′ – 100′
|
100 – 200′
|
200′ – 300′
|
300′ – 400′
|
400′ – 500′
|
|
4″
|
8 oz
|
16 oz
|
24 oz
|
1 qt
|
1 ½ gal.
|
2 gal.
|
6″
|
1 qt
|
2 qt.
|
1 ½ gal.
|
2 gal.
|
2 ½ gal.
|
3 gal.
|
8″– 12″
|
1 gal.
|
1 ½ gal.
|
2 gal.
|
2 ½ gal.
|
5 gal.
|
6 gal.
|
12″ – 16″
|
1 gal.
|
2 gal.
|
4 gal.
|
6 gal.
|
8 gal.
|
10 gal.
|
20″ – 24″
|
2 gal.
|
6 gal.
|
10 gal.
|
14 gal.
|
18 gal.
|
22 gal.
|
30″ – 36″
|
6 gal.
|
10 gal.
|
20 gal.
|
30 gal.
|
40 gal.
|
50 gal.
|
EXAMPLE: The well is
4″ in diameter, with a depth of 400 feet. The water level is 100 feet below the
surface. 400 – 100 = 300 feet. Use 1 ½ gallon of household bleach.
NOTE: In applications
where it is inconvenient to determine water depth, at least ½ gallon of
household bleach, or ¼ gallon of pool chlorine, may be used for wells up to 8″
in diameter with water estimated to be less than 80 feet deep; one gallon
should be used for similarly sized wells with water greater than 80 feet.
5. Mix the chlorine the solution above with 10 times as much water before pouring down well. Avoid
pouring strong bleach down the well.
6. Open the well cap,
or if your well has a well top seal, remove the ½” plug or air vent and use a
large funnel to pour chlorine down well. CAUTION: well caps and seals are
integral to the safety and integrity of your well. They are often regulated by
the state and local codes. Be certain to comply with all applicable codes and licensing
laws, whenever opening a well. If you are unsure of any of the following steps,
seek the assistance of a qualified or licensed well driller or pump installer
or contractor.
7. Do not attempt to remove the sanitary well
seal without the assistance of a qualified well driller or pump contractor. Do
not loosen the bolts that compress the seal.
8. Wells equipped with
a packer jet pump can be thoroughly disinfected only through the removal of the
pipe, pump and jet unit from the well.
9. As you are adding
the chlorine solution, take precautions to protect yourself from splashing
chlorine and fumes. Protect your eyes with safety goggles, and wear protective
gloves and clothing.
10. Pour the chlorine
solution down the well. Avoid pouring the chlorine solution on the pump wire
connectors. If in doubt, use dry chlorine pellets.
11. If the well is
relatively deep, the disinfectant may be dispersed to the bottom by
alternatively starting and stopping the pump several times (although dry pellets work better for this
reason). If possible, place a
garden hose in the top of the well, and turn on the faucet and circulate the
chlorine solution for 15 minutes until a strong 50 ppm chlorine residual is
detected, by using a chlorine test kit.
12. Add more bleach as
needed to bring up the chlorine solution residual in the well to 50 to 100 ppm.
13. If possible,
circulate the water from the well by connecting a garden hose to a nearby hose
bib or sill cock, and feed the water back down into the well. This will also
wash down the sides of the well and ensure proper mixing. After approximately
15 minutes a strong chlorine odor should develop. To be more precise use a
chlorine test kit to make sure the chlorine is over 50 ppm.
14. Water should be
pumped from the well into the pressure tank and plumbing system.
15. All water faucets
should be turned on in the house and all outside fixtures and hose bibs
including fire hydrants, watering troughs, and other supply lines to other
buildings, until a 50 ppm chlorine residual is detected.
16. After the chlorine
has been left in the well (and the plumbing system if applicable) for a minimum
of 6, up to 12 hours, the chlorinated water can be discharged. Large
amounts of chlorinated water should not be discharged into the septic tank, or
onto lawns or gardens.
If possible, discharge
as much of the water as possible through an outside faucet with a hose
attachment. Do not discharge the chlorinated water into streams or rivers. The
small amount of chlorinated water, which remains in the household plumbing, can
be discharged into the septic system, but first flush the water.
18. Backwash water
softeners; flush the water heater, and replace all filters if present.
19. For wells and
piping systems that have bacterial contamination or have been flooded,
re-sample the water and retest for coliform, after all the chlorine residual is
gone.
20. The water should
be tested 2 to 3 weeks after sanitizing. If bacteria, iron bacteria, sulfur, or
other problems recur, contact your well water professional for further
treatment.
NOTE: For heavily
iron-fouled wells, severe contamination with biofilms or slime, or excessive
levels of hydrogen sulfide gas, apply a 100 ppm or 200 ppm residual by
multiplying the chlorine bleach used by 2 or 4 times.
Well System Diagram
Wells with submersible
pumps have pipes that either enter in through the top or through the side. Many
wells are underground or in vaults in areas with freezing temperatures.
Frequently Asked Questions about Chlorinating your Well
What Precautions
Should I Take before a Chlorination is Started?
If you are not
familiar with your well or well construction, consider hiring a licensed well
driller to shock chlorinate.
Should you decide to
shock chlorinate your well yourself, take the following precautionary measures:
1. Concentrated
chlorine solutions for shock chlorination can be dangerous. Because of the
volatile and corrosive nature of the concentrated chlorine solution, it is
important to wear eye goggles, protective clothing, rubber gloves, and
boots.
2. Mix and add
chlorine solution in a well-ventilated area. High chlorine levels in water
after shock chlorination. Make sure that your family or pets do not use
the water during the chlorination process.
3. Preventing electric
shock from the water pump. Before removing the well cap or cover, turn the pump
circuit breaker off. Wear waterproof rubber boots.
4. Shock chlorinating
your water supply system can potentially damage your pressure tank,
some filters and filter media, or water softener, so bypass these systems if
possible.
5. Before you begin,
shut off water to all carbon filters and reverse osmosis units attached to
your household water lines and a bypass water softener or iron filter.
When Can I Use the
Water Again?
Make sure to flush 4
well volumes before using the water:
4” well diameter has
70 gallons per 100 ft of depth
6” well diameter has
150 gallons per 100 ft of depth
8” well diameter has
260 gallons per 100 ft of depth
Wait for one to two weeks
aftershock chlorinating the water supply system and then retest for total
coliform and E. coli bacteria.
If the test results
show the absence of coliform bacteria, the water is safe to drink.
However, if the test
results show the presence of coliform bacteria, the source(s) of contamination
should be identified and eliminated through a licensed well driller/contractor
or a continuous disinfection treatment system should be installed.
What Type of Chlorine
Bleach Should Be Used?
For best results use a
powdered bleach or pellets that is certified for drinking water. However,
it is also OK to use unscented household chlorine bleach with at least 5%
sodium hypochlorite found in supermarkets.