The drinking water inside two Newark homes contained almost four times the allowable federal level for lead, despite using nationally-certified filters meant to eliminate dangerous levels of the contaminant, state officials said.

The test results alarmed officials across New Jersey and in the federal government, prompting the city’s first large-scale distribution of bottled water to 14,000 potentially affected households.

“We’re totally in uncharted territory,” Newark spokesman Frank Baraff said.

It’s too soon to say why the PUR faucet filters at two of three tested homes did not work. Newark is conducting additional sampling to explain the unexpected turn of events in the now nearly three-year water crisis.

The homes were tested in July and again last week with the results showing that even after the water coursed through the filter, it still contained lead levels above the federal limit.

One of homes contained 1,600 parts per billion of lead before the filter and 57.9 parts per billion post-filtration. The other home had 112 parts per billion of lead pre-filter and 50 parts per billion post-filtration, state officials said.

The results raise a new set of questions since the 38,000 faucet filters that Newark officials have distributed since October are certified to remove up to 150 parts per billion of lead. No amount of lead is safe but the federal government sets a federal action level of 15 parts per billion. If more than 10% of sampled homes are above the threshold, water systems must inform the public and take action.

“There are so many variables to consider when you start investigating these types of things, one of them is how much lead is in that water,” said Rick Andrew, director at the NSF water systems program, an independent public health organization that certifies water filters.

Studies conducted in Flint, however, show filters have effectively removed much higher quantities of lead -- as high as 10,000 parts per billion, according to Marc Edwards, who teaches civil engineering at Virginia Tech and helped expose the Flint water crisis.

“Every time we tested them in Flint, they were effective,” Edwards said. “They work the vast majority of the time. You’re better off with a filter than without.”

State and city leaders -- prompted by the U.S. Environmental Protection Agency -- moved quickly to distribute bottled water after the results came back on Friday.

The EPA said brand new filters were installed during last week’s second round of testing to eliminate the possibility the filters weren’t installed properly or had a defect.

“The second round of testing used new filters to rule out human error and/or manufacturer defects,” the EPA said. “Results of that analysis again indicated that the filters may not be reducing the levels of lead as anticipated."

Officials with Gov. Phil Murphy’s administration said the sample size was too small to draw conclusions about whether the issue was related to the water’s chemistry or a bad batch of filters. But it’s clear the problem is not caused by improper installation.

A state official said based on the tests, there was no evidence of widespread filter failure but the Department of Environmental Protection was overseeing additional testing to get closer to an answer.

“When you have a result like this that calls into question the ability of a filtration device that is heavily relied upon through out the country -- they are NSF-certified filters -- when you run into that kind of question, it’s a big moment so we want to make sure we are responding appropriately,” an administration official said.

Newark’s source of lead is more than 15,000 old lead pipes that connect underground water mains to homes. One of the city’s water treatment plants, the Pequannock plant, failed at properly treating the water which caused corrosive water to flow through the distribution system and eat away at the lead infrastructure.

Lead can take several forms. Particulate lead are little pieces of lead in larger chunks or smaller particles. Soluble lead is dissolved in the water. Certified lead filters are supposed to absorb both types of lead.

The EPA said testing results showed lead coming through the filter in the the two homes was mostly particulate lead and “likely a result of the unstable pipe scale from the previous corrosion control treatment.”

Edwards said filter failure is extremely rare but can happen when there’s a bad batch or if the lead particles are so small they pass through the filter.

“We have found a few instances where particles are very, very small and they’re not removed as effectively and we have found waters where more than 15 parts per billion will go through some of the filters,” he said. “That’s an unusual case; maybe Newark is an unusual case.”

Read more of NJ.com’s coverage of New Jersey water issues here.

Karen Yi may be reached at kyi@njadvancemedia.com. Follow her on Twitter at @karen_yi or on Facebook.

Get the latest updates right in your inbox. Subscribe to NJ.com’s newsletters.