The alert was issued Nov. 7 when DEP found high levels of giardia in the Shenango River, the water treatment plant’s water source. At that time, authority employees said they needed until Nov. 21 to inspect and repair the filtration system, which DEP said wasn’t functioning at full capacity.

DEP’s tests of the treated water were inconclusive that giardia was present, but the boil alert was issued as a precaution, said Eric Buzza, an operations specialist with the authority’s engineer, Gannett Fleming Inc. of Mercer.

Those test results may have been inconclusive because an aluminum-based chemical called flock used to remove contaminants from the river water could have interfered with the presence of giardia, Buzza said.

The flock may not have filtered the water properly, but it wouldn’t have made it to the treated water supply, he said.

When DEP tested the untreated water and filtration system about two weeks ago, it tested only one of the four filters and that filter happened to be one that wasn’t functioning properly, said Thomas L. Thompson, a senior project manager with Gannett Fleming.

If DEP had tested a different filter that was working at full capacity, the test results wouldn’t have been inconclusive and a boil alert may not have been issued, Thompson said.

The water authority board will meet Tuesday to discuss hiring a team of specialists from Thiel to investigate the water situation, including how and why it happened and how to ensure it doesn’t happen again.