PITTSBURGH—The Pittsburgh Water and Sewer Authority has warned residents that a man is apparently posing as an employee following a bizarre incident involving an elderly woman who let the man into her home.

Authority officials say real employees wear a uniform, carry photo identification and have vehicles marked "PWSA" with white-and-blue municipal license plates.

Officials say the suspicious incident happened about 1 p.m. Wednesday when a man knocked on an elderly woman's door and said he needed to check her water pressure.

The man wore a blue jacket and pants and was using a portable radio and threatened to shut off the woman's water service if she didn't let him in.

Once he got in, the man took the woman to the basement where he told her to count slowly to six as he left. She wasn't harmed.