Page 290 - Water Engineering Hydraulics, Distribution and Treatment

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Chapter 9
Investigation revealed that the funeral home had been
systems, the probability is great. Cross-connections exist for
these reasons:
of human “remains” as part of the embalming process. The
1. Plumbing is frequently installed by persons who
aspirator connected directly to the water supply system at a
are unaware of the inherent dangers of cross-
faucet located on a sink in the “preparation” (embalming)
connections.
room. Water flow through the aspirator created suction that
2. Oftentimes, connections are made as a simple matter
was utilized to draw body fluids through a hose and needle
of convenience without regard to dangerous situa-
attached to the suction side of the aspirator.
tions that might be created.
The contamination of the funeral home potable water
supply was caused by a combination of low water pressure
3. Connections are made with reliance on inadequate
in conjunction with the simultaneous use of the aspirator.
protection such as a single valve or other mechanical
Instead of the body fluids flowing into the sanitary drain,
device. Cross-Connection Control using a hydraulic aspirator to drain fluids from the bodies
they were drawn in the opposite direction—into the potable
To combat the dangers of cross-connections and back- water supply of the funeral home (see Fig. 9.1).
flow connections, education in their recognition and preven-
tion is needed. First, plumbing installers must know that
hydraulic and pollutional factors may combine to produce 9.2.2 Sodium Hydroxide in the Water Main
a sanitary hazard if a cross-connection is present. Second, A resident of a small town in Alabama jumped in the shower
they must realize that reliable and simple standard backflow at 5 a.m. one morning, and when he got out his body was
prevention devices and methods are available that can be covered with tiny blisters. “The more I rubbed it, the worse it
substituted for convenient but dangerous direct connections. got,” the 60-year-old resident said. “It looked like someone
Third, plumbing installers must understand that the hazards took a blow torch and singed me.”
resulting from direct connections greatly outweigh the con- He and several other residents received medical treat-
venience gained from a quick and direct connection. ment at the emergency room of the local hospital after the
public water system was contaminated with sodium hydrox-
ide, a strong caustic solution.
9.2 PUBLIC HEALTH SIGNIFICANCE OF
CROSS-CONNECTIONS Other residents claimed that “it [the water] bubbled up
and looked like Alka Seltzer. I stuck my hand under the
Public health officials have long been aware of the threat faucet and some blisters came up.” One neighbor’s head was
to public health that cross-connections represent. Because covered with blisters after she washed her hair and others
plumbing defects are so frequent and the opportunities for complained of burned throats or mouths after drinking the
contaminants to invade the public drinking water through water.
cross-connections so general, enteric illnesses caused by The incident began after an 8 in. (200 mm) water main
drinking water may occur at most at any location and at that fed the town broke and was repaired. While repairing the
any time. water main, one workman suffered leg burns from a chemical
The following documented cases of cross-connection in the water and required medical treatment. Measurements
problems illustrate and emphasize how cross-connections of the pH of the water were as high as 13 in some sections of
have compromised water quality and public health. the pipe.
Investigation into the cause of the problem led to a
nearby chemical company that distributes chemicals such
9.2.1 Human Blood in the Water System
as sodium hydroxide as being the possible source of contam-
Health department officials cut off the water supply to a ination. Sodium hydroxide is brought to the plant in liquid
funeral home located in a large southern city after it was form in bulk tanker trucks, transferred to a holding tank, and
determined that human blood had contaminated the fresh- then pumped into 55 gal (208 L) drums. When the water main
water supply. The chief plumbing inspector had received a broke, a truck driver was adding the water from the bottom
telephone call advising that blood was coming from drinking of the tank truck instead of the top, and sodium hydroxide
fountains within the funeral home building. Plumbing and backsiphoned into the water main (see Fig. 9.2).
county health department inspectors went to the scene and
found evidence that blood had been circulating in the water
9.2.3 Heating System Antifreeze in Potable Water
system within the building. They immediately ordered the
building cut off from the water system at the meter. City Bangor, ME, Water Department employees discovered poi-
water and plumbing officials said that they did not think sonous antifreeze in a homeowner’s heating system and water
that the blood contamination had spread beyond the build- supply. The incident occurred when they shut off the service
ing; however, inspectors were sent into the neighborhood to line to the home to make repairs. With the flow of water to
check for possible contamination. the house cut off, pressure in the lines in the house dropped