Tap water tests under review after false positive

By MARTHA MODEEN

TACOMA, Wash., Sept. 4, 2000 (News Tribune) — Tacoma Public Utilities says it is reviewing its procedures for testing tap water after a recent false test indicated one sample contained higher levels of bacteria than normal.

TPU routinely tests tap water at about 50 locations throughout the city, 200 times per month. It's not unusual to find bacteria in water samples.

But during a routine test last month, fecal coliform was discovered in a water sample taken from the northern part of the city, which would have violated permissible water-quality requirements.

Fecal coliform is a group of bacteria associated with human and animal excrement.

High amounts of the bacteria suggest the presence of disease- causing agents.

Follow-up studies proved that the test results were invalid and that neither the water nor distribution system were a problem.

An unclean faucet head at the test site — in this case, a convenience-store restroom at North 21st and Steele streets — may have thrown off the test, said Ken Merry, superintendent of TPU's water division.

But the incident prompted a series of discussions with state Department of Health officials and a review of how the utility conducts its water-quality tests.

"We're taking a hard look at our operations," Merry said. "We're evaluating all of our taps (at test sites), and we're reviewing our training techniques."

TPU officials are taking the matter seriously because they're concerned about accurately measuring water quality for the 200,000 users in the greater Tacoma area and want to avoid notifying the public about nonexistent water-quality concerns.

"Even though ... the results were reflective of a defective sample ... this was a matter of serious concern since it could have resulted in mandatory public notification," Merry wrote to utility director Mark Crisson in an Aug. 25 e-mail.

If bacteria levels in the city's water-distribution system actually were higher than normal, the public would have been notified within 72 hours as required by law.

TPU routinely runs a number of tests to check water quality, providing multiple levels of testing to detect water problems.

One is a heterotrophic plate count, a test that measures general bacteria.

Another measures chlorine levels. Both tests showed negative results in the problem sample, which prompted more testing, said John Kirner, TPU's deputy superintendent of the water division.

But as a result of last month's faulty test, TPU is considering spending $50,000 to $100,000 to install new test sites at its water distribution pipes, as the City of Seattle has done.

That would be a big switch from the utility's long-established procedure of checking tap water at homes, convenience stores and businesses throughout the city.

TPU also is retraining its operators in proper procedures for collecting water samples, reviewing procedures for washing hands, cleaning faucet heads and letting water run for few minutes to collect accurate test samples.

"There'd be a lower risk of getting invalid data," said Merry, describing the benefit of a new system.

TPU is reviewing its biennial budget and would make its request to the City Council.

TPU last notified the public of a water-quality problem in 1997, when water in the Prairie Ridge area registered too many particles of debris in a test that measures cloudiness of water.