Backflow certification

Definition

The separate credential a plumber needs to test and certify the devices that protect drinking water.

Why It Matters

Backflow testing is annual, mandated by the water authority, and billed per device, which makes it the closest thing residential plumbing has to a subscription. A shop with a certified tester and a maintained device list has a route that renews itself; one without subcontracts the work and hands the customer relationship to whoever shows up. Ask how many devices are on the list, what share were retested last year, and whether the certification sits with the seller or with a technician who is staying.