Backflow pass/fail calculator, and what ASSE 5110 actually covers

Pick an assembly, type in what your gauge shows, and every reading is graded against the baseline thresholds — including the calculated buffer on the reduced pressure families. This is the shipped rule engine, not a marketing copy of it, so the verdict here is the verdict a report gets.

Grading readings is the fast part; the report is the rest of the job. Open the generator to attach these readings to a facility, an assembly serial number, repairs and retest, signatures and a one-page PDF.

These are separate documents, written for separate audiences, and mixing them up leads to claims nobody can support — including software claiming to be "ASSE certified", which is not a thing that applies to a report generator.

Where field pass/fail numbers actually come from

The minimum differentials a tester records against come from the field test procedure the authority having jurisdiction adopts — commonly drawn from USC Foundation and AWWA material, state program rules, and the manufacturer's instructions for that assembly. That is why two neighbouring purveyors can hand you procedures that differ in detail, and why software that hardcodes one set of numbers eventually gets someone in trouble.

Detector assemblies are not a third rule family: they inherit the parent family's procedure and add the bypass meter and bypass assembly to the paperwork. Field detail for each type lives on the RP/RPZ, DCVA and PVB reference pages.

Every number the calculator and the generator use, in one place. These are read from the same constant the app runs on, so this table cannot drift out of date relative to the product.

The rules that matter as much as the numbers, because they are where reports usually go wrong:

• A missing reading is incomplete, not a failure. An unrecorded number is not evidence of a defect, and reporting it as one is not defensible.
• The overall result is derived, never selected. There is no control anywhere in the app that marks an assembly as passing; the status follows from the readings and the shutoff toggles.
• Failures carry structured reasons. Each failure has a code and a sentence stating what measured what against which minimum, so the report says why rather than just "failed".
• Displayed values round to one decimal; stored values do not. Rounding for display never changes the number the verdict was computed from.
• A retest does not erase the first test. The failed initial readings, the repairs and the final retest all persist, and a successful retest reports as passed after repair.

Use these as starting points and treat your own purveyor and state program as the deciding authority. Links are to the organisations' own sites; confirm current editions there rather than relying on any third-party summary, including this one.

• ASSE International — plumbing product standards and the Series 5000 professional qualifications standards.
• USC Foundation for Cross-Connection Control and Hydraulic Research — field test procedures, approved-assembly information and its cross-connection control manual. See the USC reference page for what it publishes.
• American Water Works Association — cross-connection control practice guidance widely referenced by utilities.
• US EPA drinking water regulatory information — federal context for state primacy programs.
• Your water purveyor's cross-connection control program — the form, the deadlines and the accepted procedure.