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IPC 608
Validated against the standard.
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How it works
Enter your values
Type in your inputs — the app fills code tables and constants for you, so there's nothing to look up.
Get a code-checked result
Instant answer with a clear PASS / FAIL and the exact IPC 608 reference behind every number.
Save & export
Keep a history of calculations and export a clean PDF report to share or attach to a permit (Pro).
What this calculator does
Backflow can pull contaminants into the potable water supply, so the IPC requires the right protection for each cross-connection. This app helps you choose the correct backflow assembly by matching the degree of hazard and the type of backflow to the right device.
Matching device to hazard (IPC 608)
- Air gap — the most reliable separation, where a physical gap is possible.
- Atmospheric / pressure vacuum breaker (AVB / PVB) — back-siphonage protection, common on irrigation.
- Double check valve assembly (DCVA) — low-hazard back-pressure and back-siphonage.
- Reduced pressure zone (RPZ) — high-hazard protection where contamination would be a health risk.
Worked example
A boiler with chemical treatment is a high hazard with possible back-pressure, so an RPZ assembly is required — a double check would not be sufficient for that hazard level.
Related calculators
Size the supply it protects with the water pipe sizing calculator and totals with the fixture unit calculator.
Backflow prevention FAQ
What decides which device I need?
The degree of hazard (low versus high) and whether the risk is back-siphonage, back-pressure, or both. IPC 608 maps these to the acceptable assembly types.
When is an RPZ required?
For high-hazard cross-connections — where backflow could carry a health risk — and where back-pressure is possible. A reduced pressure zone assembly is the highest level of mechanical protection.
What is the difference between an AVB and a PVB?
Both protect against back-siphonage, but a pressure vacuum breaker may be installed under continuous pressure, while an atmospheric vacuum breaker may not.
Does it work offline?
Yes, it runs 100% offline with no account. Free with rewarded ads; a one-time $2.99 Pro unlock adds PDF export and saved history.
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