Chance of getting ill may be minuscule
Public health officials said yesterday that there is little risk of people in Greater Boston developing intestinal illness — even if they accidentally ingest a small amount of tap water.
The boil-water order remains in place because a small portion of the water flowing through pipes is essentially pond water, and while the water is being heavily chlorinated to kill off bacteria, health and environmental officials say it is not advisable to drink.
There are two reasons: the high chlorine levels, and officials cannot know for sure that bacteria levels are safe until test results come back, likely today.
“We don’t expect an outbreak’’ of intestinal illness, said Dr. Al DeMaria, state epidemiologist for the Department of Public Health.
Boiling water and other measures are “entirely precautionary,’’ he said. “People should keep up the measures but they should not be overly fearful.’’
State and Boston health officials said they have not detected any outbreaks of intestinal illness from contaminated water, nor do they expect to at this point, given the long incubation period of water-borne diseases. It generally takes five to seven days for people to get sick after drinking dirty water.
“If people are feeling ill now, it’s not from the water,’’ said Dr. Anita Barry, director of the infectious disease bureau for the Boston Public Health Commission. “People should not be heading to the ER.’’
Both the Boston and the state health departments have surveillance systems designed to detect outbreaks of illness.
Hospital emergency rooms send daily electronic reports of the sicknesses they have treated in the previous 24 hours, so health officials can monitor for surges.
For most people, drinking water contaminated with giardia or cryptosporidium, the most common pathogens found in pond water, would cause diarrhea, stomach pain, and fever that would be indistinguishable from other types of intestinal illness, DeMaria said.
The state and city do not test the water for pathogens themselves, but rely on testing from outside agencies such as the Boston Water and Sewer Commission and the Massachusetts Water Resources Authority.
Barry and DeMaria said that while the water flowing into people’s homes yesterday was being treated with sterilizing chemicals, contamination could remain in the pipes from the brief period on Saturday when some of the water from the backup supply was not yet being treated.
The MWRA began drawing water from the Chestnut Hill Reservoir Saturday night to keep water pressure high enough for firefighting and flushing toilets. That water went untreated for several hours but is now being chlorinated.
“The water is being treated, but it’s not officially safe,’’ DeMaria said.
“Everyone is being extra cautious, but we mostly worry about the people who are immune-compromised’’ and might be less able to withstand an illness, Barry said. This includes people with AIDS or who are receiving chemotherapy for cancer. “If people follow the advice and not drink water from the tap the risk would be tiny,’’ she said.
DeMaria said it is safe to wash one’s hands in tap water and then use an alcohol-based hand sanitizer.
Babies can safely nurse after their mother has showered in water from the faucet and dried off, he said. And, he said, it is OK to wash clothes in hot water and then tumble them dry.
Beth Daley of the Globe staff contributed to this report. Liz Kowalczyk can be reached at firstname.lastname@example.org.