Is there a standard rate, or does it depend on the job?
A commercial plumber can charge from $150 to $200 an hr.
A residential plumber can charge from $85-$125 an hr.
A lot depends on what needs to be done and how involved the project is.
Most plumbers in our area charge $85.00-$135.00 per hour for residential plumbing, depending on the situation. There also could be a mileage charge for out of area service.