American Society of Plumbing Engineers
http://aspe.org/

ASPE Philadelphia Chapter
http://aspephila.org/

South Jersey Mechanical Contractors Association
http://www.sjmca.org/

Mechanical Contractors Association of Eastern Pennsylvania
http://www.mcaepa.org/

Pennsylvania Association of Plumbing Heating & Cooling Contractors
http://www.paphcc.org/legislation/index.html