If you just got a notice or you're trying to figure out what device you have, start here.
All guides
What to Do When You Get a Backflow Test Notice
A step-by-step guide to the annual notice from your water district: what it means, deadlines, and how to get compliant fast.
Read guideWhat Does a Backflow Preventer Do?
How backflow happens, how the main assembly types stop it, and why California requires annual testing.
Read guideRP, Double Check or PVB: Which Device Is Right?
Side-by-side comparison of the common assembly types, the hazards each is approved for, and installation rules.
Read guideMore quick answers are on our FAQ page.