A Quest for Even Safer Drinking Water
The New York Times
August 26, 2013
A Quest for Even Safer Drinking Water
By PETER ANDREY SMITH
UNIONTOWN, Pa. — On a muggy Friday afternoon in a strip mall parking lot, as thunder echoed in the Alleghenies and cottonwood seeds floated on the breeze, Lee Stanish, 32, a postdoctoral researcher at the University of Colorado Boulder, and Natalie Hull, 24, a lab manager, stepped out of a white van, its hood plastered with dead insects.
After a brief conversation with a chain store manager, the two women retrieved a large black container from their van and wheeled it into the bathroom. Ms. Hull opened the faucet and let the cold water run. The two snapped on disposable gloves, unpacked their equipment, and began collecting tap water.
Ms. Hull checked the water temperature and filled water in a vial of formaldehyde for cell counts. Dr. Stanish placed another vial of water in a portable chlorine meter for analysis. “We’re in and out in about 10 minutes,” she said. Ms. Hull flipped the faucet off. On to the next tap.
By nightfall, the van would be loaded with close to 30 gallons of water sampled from dozens of locations across the Ohio River Valley. Dr. Stanish and Ms. Hull planned to set up a mobile laboratory in a hotel room in Morgantown, W.Va., all in an effort to understand a hidden underground ecology where organisms eke out a living in dark, cool pipes loaded with chlorine.
“What we know so far is that it’s usually very clean,” Dr. Stanish said. “But it’s a disturbed environment.”
The 53,000 water utilities in the United States deliver some of the safest drinking water in the world — a public health victory of unrivaled success that began in 1908 with chlorination campaigns in Jersey City and Chicago. Still, millions of individual cases of waterborne diseases occur annually and related hospitalization costs approach $1 billion each year. In 2007 and 2008, the most recent years for which figures are available, the Centers for Disease Control and Prevention recorded 164 waterborne disease outbreaks, almost entirely from protozoan cysts of the parasite Cryptosporidium.
New rules from the Environmental Protection Agency, instituted after earlier outbreaks, have led New York City and other municipalities with unfiltered surface reservoirs to begin zapping tap water with ultraviolet light to inactivate organisms like Cryptosporidium that resist chlorine-based treatments.
The water supply system remains a deteriorating, mostly subterranean infrastructure so complex that in many municipalities officials can’t even say where all the pipes are laid. The need for upgrades has never been greater, a report issued this year by the American Academy of Microbiology said, but they first want to understand what’s living down there.
“We have done the right thing with water treatment,” said Joseph O. Falkinham III, a microbiologist at Virginia Tech. “What we have now is an unexpected consequence of doing the right thing.”
That’s why scientists like Dr. Stanish and Ms. Hull drove hundreds of miles this summer to collect tap water in 20 municipalities. Their eight-day road trip, which started in Ohio, traced a clockwise arc down through Fairmont, W.Va., and Hazard, Ky., before ending up back in Cincinnati. The field work, led by Norman Pace, a biologist at the University of Colorado Boulder, and financed by the Sloan Foundation, is beginning to map the ecological niches favored by certain aquatic organisms, which could lead to better screening methods and better water treatment.
Chlorine-based disinfectants destroy harmful cellular organisms that cause illness — eliminating infectious diseases like typhoid, cholera and dysentery — but to call the process purification is a misnomer. The researchers estimate that between 10 and 100 million free-floating, or planktonic, organisms survive in every quart of tap water.
Despite new genetic techniques, the federally mandated method for identifying what’s in drinking water focus on coliform bacteria, which can be indicators of fecal contamination. Water managers crank up the chlorine when the bacteria are found, although the vast majority of coliform bacteria do not sicken people.
Other microorganisms in drinking water — methylobacteria, sphingomonads, mycobacteria — survive chlorine-based treatment. And many scientists fear that the use of chlorine can result in the growth of resistant and sometimes harmful microorganisms, including Legionella, the cause of Legionnaires’ disease and Pontiac fever, and the nontuberculous mycobacteria, which can infect the lungs, skin and other organs.
Mycobacteria are common inhabitants in drinking water systems, and researchers are particularly interested in the estimated 20,000 infections they cause annually. When ingested or inhaled, mycobacteria can infect the lungs of the elderly or immunocompromised individuals. The infections are sometimes an occupational hazard at indoor pools, called “lifeguard lung.”
The bacteria can be spread with humidifiers, misted supermarket vegetables, or endoscopes and other medical equipment cleaned with tap water. Dr. Falkinham, for example, has isolated genetically identical strains of these bacteria from the lungs of affected patients and from household plumbing.
The incidence has given new urgency to understanding the environment in which they thrive, or at least survive: the nitrites and sulfites, dissolved oxygen, and the entire assemblage of microbes living in pipes. If this year’s samples collected from the industrialized Ohio River Valley resemble those collected last year, when two postdoctoral researchers, Eric Holinger and Kim Ross, made a similar water-sampling expedition along the relatively unpopulated areas along the Arkansas and Mississippi rivers, then the two systems will serve as a representative whole.
The researchers’ guerrilla sampling tactics — chatting up restaurant managers, scoping out public restrooms — provide a random sample and cover a broad, representative sample of taps people use on a regular basis.
What they’ve learned so far is this: Water drawn from the faucet is markedly different from the water that leaves the system’s treatment facility. “The ecology,” Dr. Pace said, “is the distribution system.”
Bacteria can evade disinfectant by slipping into an amoeba’s digestive system or inside protozoan cysts, persisting there for up to a hundred years. But many species survive in so-called biofilms — a sticky polymer made of DNA, proteins, and carbohydrates clinging to pipes like plaque. Back at the lab, Dr. Pace’s team is sequencing DNA in the water samples and finding evidence that this slime may be knocked loose, carrying organisms throughout a water distribution system.
Nicholas Ashbolt, a microbiologist at the University of New South Wales in Sydney, Australia, says pathogens exist at greater concentrations in water supply systems with more chlorine, not less, and especially with another chlorine-based treatment chloramine. In a forthcoming review, Dr. Ashbolt also identified water systems as a “hot spot” for the emergence of antibiotic-resistant microorganisms.
Cooling towers and other man-made structures, he said, not only foster colonies of mycos and Legionella, but also deadlier organisms. Stagnant waters encourage their growth, and biofilms foster genetic transfer between organisms — resistant genes become more widespread among organisms surviving in the pipes.
“My fear is that we’re increasing the likelihood of engineered environments contributing to antibiotic resistance,” he said. “Everything we do has microbial consequence. If we can better understand the ecology, then we can better manage them rather than, ‘Let’s hit them with a bigger sledgehammer.’ ”