Sampling done in hundreds of Newark homes has found that up to 99 percent of city-issued water filters are working.

Tests over the last several weeks were performed after water in two homes with lead pipes showed elevated lead levels last month.

Residents in about 14,000 homes have been receiving bottled water since mid-August.

Gov. Phil Murphy said Monday about 300 homes were tested and 97 percent of the filters worked effectively when the tap was turned on. That number rose to 99 percent if water ran for five minutes before samples were taken.

“These results are a welcome jolt of positive news,” Murphy said.

FULL COVERAGE: Newark Water Crisis

When asked why 3% of the water filters failed, officials said that they did not know why, adding that maybe it was “a bad filter or bad luck.”

Newark began passing out the filters last fall after the city's water treatment program was found to be ineffective.

The city is also involved in a $120 million project to replace 18,000 lead water service lines. Mayor Ras Baraka says that so far 900 lines have been replaced.

“Filters, orthophosphate, changing lead service lines. That’s always been our plan. It is our plan now and we won’t rest until every line is completely replaced,” the mayor said.

City officials said they would continue distributing bottled water for the time being.

Volunteers will also be going around to teach Newark residents how to properly install the filters.

People are being told not to use hot water in the filters, not to use the filter to clean dishes and to change cartridges when the device signals that it is time.