Mystery of the 'Pinhole Leak' Deepens

By Sandra Fleishman
Washington Post Staff Writer
Saturday, January 20, 2001 ; Page G01

The Washington Suburban Sanitary Commission still doesn't know what is causing the tiny copper pipe leaks plaguing some Montgomery and Prince George's county neighborhoods, but it thinks it's getting closer to an answer.

WSSC officials this week said experts hired last September are now focusing on the mineral deposits commonly found in and around the "pinhole" leaks. The experts are exploring whether the deposits are the result of interactions between copper pipe and specific chemicals used in the water-treatment, filtration and pipe relining processes, and whether the deposits are triggering the leaks.

The agency said it hopes to conclude its investigation by summer.

WSSC officials shared the results of its preliminary findings with reporters after briefing local plumbers and national copper manufacturers who formally joined forces with the agency last summer to collect data from homeowners.

Complaints about pinholes have been building over the past five years. Plumbers began to notice a surge three years ago and asked the WSSC to keep track of the problems. After one attempt in 1999, a more extensive questionnaire was prepared for plumbers and customers in July.

The latest WSSC tally shows 1,658 complaints of pinholes over the five-year period, up from the 925 homeowner complaints logged by October. In July, when The Washington Post first wrote about the pinholes, 300 complaints had come in. The WSSC has 400,000 customers.

The calls have picked up again this winter, said Billy Silk, past president of the Washington Suburban Master Plumbers Association. Silk, head of Master Plumbing and Mechanical Inc. in Silver Spring, is a member of the pinhole task force, along with representatives of the Copper Development Association. He and other plumbers see a relationship between pinholes and a change in temperature, either colder or warmer.

"Since Christmas, it's really gone gangbusters. We've [just] gotten 19 calls in less than a week," said Silk.

His mother's house in Kensington recently had its fourth pinhole. "So now we're going to have to repipe her whole house," he sighed.

WSSC officials said its experts have ruled out a number of theories for what may be causing the leaks. The discarded theories include stray electrical currents associated with wiring in the house, water pressure and speed of the water as it flows into the house.

The focus now is on understanding what's happening inside the pipes when WSSC water flows through. Different kinds of water form different kinds of protective films on the inside of old and new copper pipe, experts said. The question is how WSSC water from the Potomac and Patuxent rivers makes that film and what is causing interactions that dissolve the metal.

The agency's experts have learned from X-raying pipe samples that compounds containing iron, chloride and aluminum -- in particular, aluminum silicate -- are commonly found near the leaks. But it is not clear yet whether these solids can cause pinholes or from where the deposits are coming.

While the narrowing of the investigation seems to suggest to some that the WSSC might be responsible, albeit inadvertently, those on the task force say the situation is more complex. "Something has changed in the water or in the interaction" with the film in the pipe, said Ken Geremia, spokesman for the Copper Development Association. "It takes two." Geremia said it is also possible that the problem has more than one cause. "The bottom line is that there may be more than one mechanism," he said.

Among possible sources of the deposits are chemicals used in the water-treatment and filtration process. The head of the WSSC's labs last year said the agency has several times changed the coagulants used to filter the water, going from alum to ferric chloride to aluminum chloride.

Aluminum silicate, or particles containing aluminum and silica, is associated with certain chemical interactions with the cement linings inside pipes, according to WSSC engineers. The WSSC has been cleaning and lining old cast-iron supply pipes with cement since the mid-1980s -- and on a more aggressive schedule since the mid-1990s -- so customers don't get rusty water and to prevent further corrosion inside the pipes, engineers say.

Marc Edwards of Virginia Tech, a nationally recognized copper corrosion expert hired by the WSSC, said the investigation is raising "fundamental" questions about how corrosion occurs. "The conventional wisdom is that these deposits are good [in forming protective coatings], but when we tested that theory a year ago," in a study for Denver on whether to add aluminum silicate to its water to increase the protective layer, "we found out they were bad in some ways for copper corrosion."

Edwards advised Denver not to add aluminum silicate to its water.

The next step in the WSSC investigation "is to determine whether [the deposits] can cause [pinhole] pitting. . . . It's an extremely complicated problem," said Edwards.

The WSSC has said that few broad changes have been made in its water-treatment process over the past 10 years other than to keep improving water quality. On a daily basis, small changes are made to treat differences in the quality of the water coming into the treatment plants. That quality is affected by factors such as how much rain falls and how polluted or muddy the water is. The 82-year-old agency prides itself on meeting or exceeding every federal water quality and safety standard.

"As EPA regulations get more stringent, as we get cleaner water, that can possibly impact this film as well," WSSC spokesman Chuck Brown said.

He emphasized that "while we have made considerable progress and what we know now might lead some to jump to a conclusion, you can't jump to any conclusion." Brown said the agency hopes to wrap the study up in four to six months.

An answer can't come soon enough for families who have been tortured by the tiny leaks or for families who fear them. Unlike most isolated pipe failures, those popping up in the WSSC's service area seem to occur over and over in each house, driving homeowners to distraction and requiring extensive repairs. The leaks often go undetected until accumulated water bursts through ceilings.

The failures also sometimes seem to spread like a plague: When one house on a street gets them, others seem to follow.

Plumbers generally recommend repiping after three or four leaks, at a cost that can run from $3,000 to $6,000 or more. But Brown this week recommended "not doing a total replacement until we can conclude this investigation."

Homeowners insurance covers only damages from pipe failures, not pipe replacement. Because insurance companies limit claims from non-weather-related damage, residents who file multiple claims run the risk of being dropped.

The WSSC's team of experts is currently analyzing the WSSC's water chemistry, filtration and delivery systems and those of neighboring water authorities, which say they are not experiencing problems. The experts are also studying pipe samples from affected houses. The WSSC recently asked employees whose homes don't have pinholes to donate pipe samples for comparison tests.

Both the local plumbers and the copper manufacturers, who are conducting a separate study, praised the WSSC for its progress. "We're getting a lot better help from the WSSC," said Silk. "I feel like they do know that there is a problem and that it is their duty to find out what is going on. But I'd love to see it go a lot faster."

The WSSC's latest data confirm earlier findings:

• Customers living in the older communities of Bethesda, Chevy Chase, Silver Spring and Beltsville are reporting the most occurrences. The most reports -- 133 -- in any Zip code have come from customers in west Bethesda (20817).

• Nearly 80 percent involve houses built before 1970.

• Most are in cold-water horizontal copper piping.