|
| Page 1 2
3 |
| 1.0 Introduction
and Background |
| The incidence of rotten egg odor
or black water in water lines is due to the reaction of sulfates and
microorganisms in water. To determine the source of the odor, it is
important to check to see whether the cold water contains odor, or
just the hot water. Run the hot water to notice the odor. Then move
to another faucet and run the cold water. If the cold water has an
odor, then the source is in the cold water. If the hot water alone
has odor, then the odor is occurring primarily in the water heater. |
 |
| Black or rusty slime, and/or
stringy-appearing growths on the sides of toilet flush tanks
(above) may indicate the presence of bacterial growth. Water
heaters (right) are prime sources of odors when bacteria react
with the anode rod inside. |
|
 |
| Odors Caused by Bacteria |
| Some waters contain an excessive amount of sulfates
with various strains of sulfate bacteria. These bacteria, harmless
to health, will react in stagnant water that has been depleted of
oxygen, and will produce hydrogen sulfide gas, using the hydrogen
ion from the anode cathode reaction. Almost all water heaters have
“anode rods” which in a cathode-anode reaction, produce
excess ions that wear off the anode rod and adhere to the inside glass
lining of the water heater, preventing corrosion. The greater the
activity of the anode, the greater the amount of hydrogen ion and
hydrogen sulfide gas. These bacteria (typically the “desulfovibrio”
or a related species) can be killed with adequate amounts of chlorine
by periodic shock chlorination. |
| These bacteria cannot grow in the
presence of atmospheric oxygen, which may account for their not being
noticed in cold water lines. |
| Odors Can Develop in City Water
High in Sulfates & Low in Chlorine |
| If your water comes from a municipal (“city”)
water source, the water is usually chlorinated and stored in above
ground atmospheric holding or storage tanks. It is unusual that this
type of water will have produce odors in the cold water lines. It
can occur in some situations however, if your home is located at the
end of the distribution, far away from the chlorination station, and
the piping is ductile iron pipe. |
| Even though the water entering a pipeline from the city
water treatment plant can be free of odor, the water may develop odors
directly in the distribution line. This can be caused by old iron
distribution systems that provide an environment for the sulfate bacteria
to grow. Increased bacterial growth depletes both the oxygen and the
chlorine residual in the piping. By the time it reaches the house
it can be free of chlorine residual and odors can easily develop. |
| Odors can develop even in cold water piping in the
home, especially in galvanized iron piping. Often iron piping in the
house is of an older age and can be corroded, providing a good environment
for the bacteria to grow and odors to develop. If there is an odor
in the cold water, and the source is chlorinated city water, its best
to trace and see if the piping is iron piping, and then replace it
with copper. As a first step to this process, one can chlorinate the
piping and sanitize it, and see if the odor can be eliminated. |
| Other Odors |
| Other causes for odors are very high chlorine concentration
(leading to chlorine odors), or algae and other organic material in
the city water source itself. There is nothing the homeowner can do
on a one-time basis to correct these types of odors. For these problems,
one could install a filtration system or if that isn’t feasible,
contact the city water utility and tell them what you are experiencing
to see if it can corrected at by the water utility. |
| 2.0 Procedure
for Chlorinating Home Piping Systems to Eliminate Sulfur Odors in
Cold Water Piping on City Water |
| If there is a sulfur odor, or “rotten-egg”
odor in the cold water, then you can use shock-chlorination to either
temporarily or permanently eliminate the odor. Shock-chlorination
will kill the bacteria in the cold water lines and loosen up scale
and slime that may have developed in the piping. If the odor is only
in the hot water, go to Section 3 to see instructions on chlorinating
and about water heaters. |
| Unless you are familiar with your plumbing system and
handling chlorine you should not attempt to chlorinate your own piping.
This should only be attempted by a licensed water treatment professional
or plumber. |
| There are two methods of filling
a household or other piping system with a chlorine solution: |
| Method 1: Use a standard
centrifugal pump, sump pump or other pump and pump in a 80 to 100
ppm chlorine solution into a household piping system that is de-pressurized,
filling the pipes up with the chlorine solution. This involves
shutting the water pressure off from the street, and draining the
household pipes and then pumping in a solution of chlorine from a
clean, new plastic trashcan or other clean container. The fixtures
and faucets are opened and the solution is pumped until the chlorine
solution is present in all the fixtures, including the water heater
and hot water lines. To chlorinate a home that is 2 stories or less,
use a pump that can develop at least 20 psi at 5 gallons per minute.
After a chlorine residual of 50 to 100 ppm is detected at each faucet
or fixture (using a high-range chlorine test kit, not a pool or hot
tub test kit) the chlorine solution is allowed to remain in the pipes
for 12 to 24 hours. |
| Method 2: Use a high-pressure
metering pump. Professional water treatment specialists and
distribution system operators would use this method. This involves
leaving the water system under pressure and using a high pressure,
low-volume metering pump to inject a concentrated chlorine solution
under pressure, while the water is running in the house. After a chlorine
residual of 50 to 100 ppm is detected at each faucet or fixture (using
a high-range chlorine test kit, not a pool or hot tub test kit) the
chlorine solution is allowed to remain in the pipes for 12 to 24 hours.
This method saves time and is as effective as Method 1. |
| Method 1 – Shock chlorination
of piping systems by injecting a 100 ppm chlorine solution using a
centrifugal, sump pump or other pump: |
| 1. |
Shut off the main line coming in to the
house. Identify an outside hose bib or other opening in the incoming
piping. If no hose bib or opening exists, install a ½”
threaded opening and a hose bib into the main line to use for injecting
the chlorine solution. Open up several of the faucets or taps in the
house and drain the water from the household piping. |
| 2. |
Hook up pump using garden hose or other hoses to the main line. |
| 3. |
Mix 1 ounce of household bleach or ½
ounces of pool chlorine (12% sodium hypochlorite) for every 4 gallons
of water in a clean trashcan or other plastic container. This will
create a 98 ppm chlorine solution (or approximately 100 ppm). The
amount of solution needed will vary depending on the size of the piping,
but typically there is approximately 100 to 300 gallons of water in
most home piping systems. |
| 4. |
Run the water in the house until the bleach
solution has filled all the pipes and a strong odor of chlorine is
coming from the fixtures or faucets, both hot and cold. |
|
