Viruses Creep Into Public Water Supplies Through Leaky Pipes
By Brenda Goodman, MA
WebMD Health News
Reviewed by Louise Chang, MD
Sept. 14, 2012 -- Two new studies are making waves in the tap vs. bottled water debate.
The first study shows that the pipes that ferry drinking water from public wells to home taps may let in viruses that cause more than a million cases of stomach illness every year. It's published in Environmental Science & Technology.
The second study, in the journal Environmental Health Perspectives, shows that when viruses surge in tap water, people have a 30% higher risk of getting nasty stomach bugs that cause vomiting and diarrhea.
The studies stem from the same government-funded research project. It's one of the largest ever to look at illnesses tied to public water supplies.
"As an individual looking at these results, I was alarmed," says researcher Frank Loge, PhD, an environmental engineer at the University of California at Davis.
"The drinking water that we have in the U.S. is very, very good relative to other countries, and so I don't want people to get the impression that we have a really bad problem relative to other parts of the world," Loge tells WebMD.
"It really made me rethink whether I want to drink bottled water vs. tap water," he says, noting that bottled water has its own problems. For one, it comes in plastic bottles that are often sent to landfills. Some bottled water comes from municipal water sources.
But some bottled water is bottled close to its source, and doesn't travel through leaking pipes, which may ultimately render it cleaner.
Until more is known about bottled and tap water, Loge says, the question of which one is safer is still murky.
Looking at the Safety of Public Water Supplies
The project compared 14 public water systems in Wisconsin. Like more than 147,000 towns in the U.S., all the communities in the study pumped their public water from underground pools called aquifers. And like many of communities that rely on groundwater, the 14 in the study didn't disinfect the water after it left those large wells.
For the first year, eight of the communities installed powerful ultraviolet (UV) lights to clean the water as soon as it left the underground pool. The other six continued to have no disinfection.
Scientists sampled water each month from the underground pool, from an area that was just past the UV disinfection, and then from six to eight home taps. The second year, the towns swapped. The eight towns that used UV disinfection turned their systems over to the six that didn't have them. That let scientists compare how well the UV systems worked to clean the water.
After the two years of watching the water, researchers found that no community had consistently clean or consistently contaminated water.
When they plugged their measurements into models that estimate risk, they found that nationwide, drinking water that's tainted as it travels through pipes to people's homes could be responsible for as many as 1.1 million cases of acute stomach illness each year. That's a level of illness that's 559 times higher than what the EPA considers acceptable for public drinking water supplies.
Mark A. Borchardt, PhD, a microbiologist with the USDA's Agricultural Research Service, says that normally, the average person can expect to get sick with a stomach bug once or twice in a given year. People who drink water from public systems that aren't disinfected can expect to see that risk climb by about 30%. Looking at the numbers another way, that means as many as 1 in 5 cases of stomach illness each year may be caused by contaminated water. That number may be as high as 2 out of 5 cases in children.
Public Water Infrastructure Problems
Researchers were concerned about what happens to water on its way to the tap because much of the public water infrastructure in the U.S. is in a state of disrepair. In a 2009 report, the American Society of Civil Engineers gave America's drinking water systems a D- grade and stressed the need for more money to replace crumbling facilities and plumbing.
To make matters worse, researcher Mark A. Borchardt, PhD, a microbiologist with the USDA's Agricultural Research Service, says many pipes that carry drinking water are laid close to lines that carry untreated sewage. Like the water pipes, the sewer lines are also often not in great shape.
"If you dig up soil around drinking water pipes, you can find all sorts of pathogens that come from leaking sewer lines," Borchardt says. Pressure changes may then suck some of those disease-causing germs into the drinking water.
Advice for Safer Tap Water
Smaller towns and rural areas are more likely than larger cities not to disinfect their water. To find out if your water is disinfected or not, contact your municipal water supplier.
If you live in a community where groundwater isn't disinfected, Loge says there are home systems that can be installed to clean water before you drink it.
Those systems range from $100 to $500 in price and usually need to be professionally installed.
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