Specializing in preventing and solving Legionella problems, he has investigated hundreds of building water systems, recommended remedial strategies for plumbing systems, designed sampling programs, written Legionella management plans including HACCP plans, and served as an expert in more than 50 legal matters pertaining to Legionnaires' disease, with deposition and trial testimony for both plaintiffs and defendants.

Freije earned a BS in mechanical engineering from Purdue University and a post baccalaureate certificate in epidemiology and biostatistics from Drexel University. He also completed a water treatment certificate program at California State University, Sacramento, a graduate course in Microbiology at Montana State University, and is a Certified Water Specialist.

Freije is a member of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), American Society of Plumbing Engineers (ASPE), American Water Works Association (AWWA), International Water Association (IWA), and the Water Quality Association (WQA).

Freije has spoken at several conventions and to private groups, taught seminars, written numerous articles and two books, and has been interviewed on radio and TV. He is the editor of Legionella Enews, an international newsletter that covers outbreaks and new technology. His first book, Legionellae Control in Health Care Facilities: A Guide for Minimizing Risk, has sold in more than 30 countries. His latest book is Protect Yourself from Legionnaires' Disease: The waterborne illness that continues to kill and harm.