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300 Chapter 9 Cross-Connection Control
Other residents claimed that “it [the water] bubbled up and looked like Alka Seltzer. I
stuck my hand under the faucet and some blisters came up.” One neighbor’s head was cov-
ered with blisters after she washed her hair and others complained of burned throats or
mouths after drinking the water.
The incident began after an 8-in. (200-mm) water main that fed the town broke and
was repaired. While repairing the water main, one workman suffered leg burns from a
chemical in the water and required medical treatment. Measurements of the pH of the
water were as high as 13 in some sections of the pipe.
Investigation into the cause of the problem led to a nearby chemical company that dis-
tributes chemicals such as sodium hydroxide as being the possible source of contamina-
tion. The sodium hydroxide is brought to the plant in liquid form in bulk tanker trucks,
transferred to a holding tank, and then pumped into 55-gal (208-L) drums. When the water
main broke, a truck driver was adding the water from the bottom of the tank truck instead
of the top, and sodium hydroxide backsiphoned into the water main (see Fig. 9.2).

Chemical bulk storage and holding tanks

SODIUM
HYDROXIDE

Hose with bottom fill
Water service

Water main
break and
repair

Figure 9.2 Sodium
Hydroxide Back-Siphoned
into the Water Main “Burned in the shower”