Gibsonville - Even a state water quality expert with 29 years' experience can't guess what makes up the black gunk collecting on faucets in Walnut Crossing.

"As far as what this is, I don't have a clue," said Wade MacDonald, assistant regional engineer for the N.C. Department of Environment and Natural Resources.

MacDonald went to Joe Albino's Walnut Crossing home on Monday and filled a jug with a liter of water for testing. MacDonald then swabbed the black stuff collecting on faucets and shower heads in Albino's home and stuck those in a container for more tests.

State water quality labs will search for heavy metals - stuff such as arsenic, manganese and barium - that could be dissolved in tap water from the Walnut Crossing neighborhood.

And the black stuff goes to a lab in Raleigh for identification.

Albino and his neighbors have had problems with the water, or whatever is in it, for several years. Some type of black gunk collects on aerators, shower heads and toilets, he said.

The neighborhood along N.C. 70 in eastern Guilford County is somewhat new, similar to other nearby developments.

Once a week, Albino said, he unscrews and scrubs the faucets on his kitchen and bathroom sinks. When he or his wife clean the toilet, the black stuff collects in the bowl again a few days later.

This spring, Albino and his neighbors called on Gibsonville public works officials and sent them a signed petition asking for tests.

A crew tested chlorine levels and flushed water lines by opening hydrants. Gibsonville said everything appeared OK.

The black stuff kept coming.

Walnut Crossing residents then phoned state water quality officials.

In April, the state sent an engineer to test for bacteria and organic compounds, such as acetone - the active ingredient in nail polish remover - and benzene, an industrial solvent.

That round of tests showed no dangerous levels of bacteria or organic compounds, said Lee Spencer, regional engineer for N.C. DENR.

Still, the black gunk collected on fixtures.

Albino kept looking for help.

He called Sen. Elizabeth Dole's office and the EPA.

On Wednesday the News & Record ran a story about the neighborhood's concerns.

On Thursday morning, Albino said he received a call from a state DENR engineer to set up a time for someone to sample the water - and the goo - again.

"Don't know if it's plumbing material or cleaning solution," said MacDonald, based at DENR's Winston-Salem office.

MacDonald left a container for Albino to collect more of the black substance as it falls out of his faucets.

The liter of water MacDonald collected will be tested for the heavy metals. The black stuff will go to the state's Laboratory of Public Health in Raleigh, North Carolina's main center for environmental testing.

MacDonald said test results for both should be back within three weeks.

Until then, he hopes to go to more homes in the neighborhood for samples.

"So far, really we don't know anything," MacDonald, "I don't have anything to tell him (Albino), but hopefully in a couple of weeks we will."