You can use this page to link to other useful industry references.
Publications
Resources
Contractor
American Society of Testing and Materials (ASTM)
Plumbing and Mechanical
American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE)
P&M Engineering
American Society of Sanitary Engineers (ASSE)
Water Conditioning and Purification
Directory of Plumbing Manufacturers
Water Engineering and Management
National Sanitation Foundation (NSF)
Water and Waste Water Digest
Radiant Panel Association (RPA)
Water Quality Products
Water Quality Association (WQA)