

International Association of Plumbing and Mechanical Officials: http://www.iapmo.org/Pages/splash.aspx
NSF International: http://www.nsf.org/
PHCC: www.phccweb.org
Plumbing Manufacturers Institute: www.pmihome.org
U.S. Environmental Protection Agency: http://www.epa.gov/OGWDW/lead/index.html
State-specific guidelines:
California State Assembly: http://www.assembly.ca.gov/defaulttext.asp
State of Vermont Legislature: http://www.leg.state.vt.us/
Your complete resource for a variety of information:
Viega North America Home Page: www.viega.net