In the January 2001 copy of Fine Homebuilding on page 24, a guy has a question about size upgrades on his home plumbing lines. After answering his question, the plumber responding concludes by saying "And don't forget to install an anti-back-flow valve immediately after the main shutoff."
I have no anti-backflow valve in my house- I have a main shutoff, my meter, and then another shutoff. Are anti-backflow valves sometimes built into the meter, are they really necessary, or did somebody oops when they ran city water to my house in 1998...?
Thanks for the info!