The document provides instructions for shock chlorinating wells, tanks, and pipelines to eliminate bacteria. It recommends testing private water supplies annually for coliform bacteria, as a positive result indicates disease-causing bacteria may be present. Shock chlorination involves injecting a high dose of chlorine, then flushing the system to remove the chlorine residual and kill bacteria throughout the system. The document discusses different shock chlorination methods and cautions that it only addresses immediate bacteria problems, not the source.

1. How to Shock Chlorinate Wells, Tanks
and Pipelines
It is important to periodically monitor private water wells to
see if contamination is present. The United States
Environmental Protection Agency recommends that private
water supplies be tested annually for coliform bacteria to
detect contamination problems early. Test them more
frequently if you suspect a problem.
http://www.epa.gov/safewater/pwells1.html
Using Liquid Bleach for Chlorinating Wells

2. 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.

3. 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.

4. Coliform bacteria tests are used as an indicator
of the possible presence of disease-causing
bacteria. You can test for bacteria yourself using
one of our 18-Minute Bacteria test kits, or for a
certified test, take the sample to a licensed
laboratory in your area. Use a sterile bottle
obtained from the laboratory.

5. Sanitizing of the well, distribution & home piping
system is recommended after:
• A new well has been constructed
• Any time a well is opened for
repairs
• Floodwater 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

6. CAUTION: While shock chlorination corrects
immediate bacteria and/or odor problems in wells
and piping systems, it does not correct the source
of the bacteria. 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.

8. 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 insure
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. Periodic shock
chlorination with high doses of chlorine
How Shock Chlorination Works

9. This involves injecting into the well,
pump system, and piping a 50 to 200 PPM
dose of chlorine. The chlorine residual is
allowed to sit in the well for 6 to 24
hours, and then the water is pumped out
until the chlorine residual is gone. This
will typically eliminate the odor problem
temporarily. If the odor returns, often
within a couple of days to a few weeks,
the procedure can be repeated. If the
odor is still present after a couple of
repeated shock-chlorination procedures,
one of the other methods will need to be
used. Aeration of the water to oxidize
the hydrogen sulfide gas, combined with
periodic shock chlorination.

10. Since the bacteria that create the hydrogen sulfide odor are
usually anaerobic, or bacteria that cannot thrive in oxygen
rich environments, often aeration in a non-pressurized vented
holding tank is beneficial to eliminate the gas and drive it off
into atmosphere. This works best if the pH is low (less than
7.0) since the hydrogen sulfide gas at pH higher than 7.0 will
not easily gas off completely. If you don’t have a storage
tank or plans for one, you can also use an air-compressor vent
tank type system, which injects air under pressure and is
often used with a carbon or iron filter system.

11. Continuous Chlorine Injection
About pH and odor control:
the higher the pH, the more
chlorine, peroxide, air, or
ozone will be required. If
the pH is over 8.5, hydrogen
peroxide combined with
aeration is a very effective
method to control odors
compared to chlorine or just
aeration.
Odors can be controlled in
water by chlorination, followed
by retention or contact time
and aeration. Chlorine is a
powerful oxidizer, and while not
as powerful as ozone by weight,
is less expensive to install and
operate than ozone systems.

12. Usually 2 to 3PPM of chlorine is injected for every
1 PPM of sulfide; however, if the pH is over 7.8 it
can take up to 5 to 10 PPM of chlorine per 1 PPM
of sulfide to treat hydrogen sulfide. If the pH is
over 8.0, we usually recommend ozone or
hydrogen peroxide injection instead of chlorine
bleach.

13. For the rest of the details, please
read:
http://www.cleanwaterstore.com/
resource/how-to-guides/how-to-
shock-chlorinate-sanitize-wells/