How can lead tests on Tacoma school water move from four-digits to zero?

When Tacoma Public Schools announced Monday that recent follow-up measurements of lead in school drinking water revealed dramatically lower results than previous rounds of testing, some parents and other Tacoma residents met the news with skepticism.

How did a school like Reed Elementary — which posted a whopping 2,330 parts per billion (ppb) in a test of one water outlet performed a year ago — suddenly drop to zero high-number results when tests were repeated last week?

Mike Means of the state Department of Health office of drinking water says how the tests are performed is key.

“The challenge is, we don’t know what the protocols were,” he told The News Tribune.

That shortcoming is the subject of a Tacoma Public Schools investigation, which is looking into why previous troubling results were not brought to the attention of either school district officials or the public. Without knowing how the tests were conducted, Means said, it’s impossible to tell exactly what was going on in Tacoma schools.

But in general, he said, water testing produces the kind of scary numbers found at Reed when protocols aren’t followed precisely.

The state Health Department describes the protocols this way:

▪ First, what’s called a “first-draw” sample is taken. Water should be tested during the week, while it’s being used by students and staff, not following a weekend, holiday or during the summer when water is not in use.

First-draw samples must be taken after water sits in the plumbing system at least eight hours — usually first thing in the morning, before students arrive. This helps pinpoint areas that need further testing.

▪ Follow-up testing is recommended for all fixtures where first-draw samples show high lead levels. (The state standard is 20 ppb, but Tacoma Public Schools is currently using 15 ppb).

During follow-up sampling, the water is allowed to run for 30 seconds before the sample is taken.

Without follow-ups to simulate more realistic usage, it’s hard to know how high water lead levels really are. Even simple errors can add up, Means said.

One possibility is that particulate matter — small pieces of lead dislodged from aging pipes or plumbing fixtures — can become trapped in faucet aerators and collect over time. If someone, for example, removes the aerator during testing, that can dislodge high concentrations of lead into a testing sample.

“That is not representative of what kids drink” in a school setting over the course of a day, Means said. He said there’s a public misperception that if high numbers are reported, it means the water is permanently contaminated.

He said that while there may be high lead levels in a “first-flush” of a school’s system after water has been standing overnight or over the weekend, the effect can dissipate as water is used throughout the day.

Does that mean school custodians need to turn on the water taps every day before kids arrive?

Means said that’s been tried in some states. He said Seattle Public Schools tried installing devices that would automatically flush school water systems, but that the devices had problems.

Pinpointing problems and installing lead-free fixtures is the best solution, he added.

What should happen next?

Means said the Department of Health recommends that Tacoma Public Schools re-test wherever high lead levels registered previously. That testing is underway now. Means also recommends that the district set up a routine sampling program meant to test all schools within a three years.

That’s what Seattle Public Schools did more than a decade ago when high lead content was discovered in its school drinking water. The program was established by the Seattle School Board, which adopted a drinking water policy in 2004. It includes periodic testing of every drinking water source in every school, coupled with reporting of the results on the district website, seattleschools.org.

Tacoma Superintendent Carla Santorno has ordered immediate re-testing of all water fixtures in all Tacoma schools, and the district has pledged to complete those tests this month.

“You can be assured that we won’t get into this place again,” Santorno said, noting that the school district plans to initiate a plan for a routine, ongoing water-testing cycle.

Testing school drinking water for lead content is voluntary in Washington, so school districts are free to proceed as they wish. Tacoma Public Schools was testing in some buildings at least as early as 2010, and in 2012 the district put together a plan for more systematic testing, which began in 2013.

Even though health officials are concerned about children’s lead exposure and encourage schools to test and re-test their water outlets, they emphasize that drinking water is not the prime source of lead poisoning in American children. That distinction belongs to old lead paint that dates before 1978, and which can still be found in older homes with peeling paint.

Lead was also a byproduct of the old Asarco smelter in Ruston, which closed in 1985. Lead emissions settled into soil in Tacoma and surrounding areas, and soil is also a source of lead contamination.

This story was originally published May 3, 2016 at 6:10 PM with the headline "How can lead tests on Tacoma school water move from four-digits to zero?."