ASSE 6020 cheat sheet

Authority for a cross-connection control (CCC) program derives from state plumbing/health codes and local ordinance; the water supplier is typically the legal enforcer at the service connection.

Program elements: enabling ordinance, certified tester roster, assembly inventory, hazard classification of premises, installation/permit review, annual testing tracking, and enforcement/termination procedures.

Hazard classification drives requirements: Class 1 (no health hazard) may allow non-testable devices; Class 2 (pollution, non-health) and Class 3 (health hazard) require testable assemblies; Class 4 (toxic) requires an air gap.

New service and remodel review: premises survey assigns a containment (service-line) assembly and, where required, internal isolation assemblies at point of hazard.

Annual testing cycle: testable assemblies must be tested at least annually (or per local rule) by a certified tester; the program tracks due dates, late notices, and noncompliance escalation.

Records retention: maintain test reports, tester certification numbers/expiration, assembly make/model/size/serial, location, and hazard classification; typical retention is 3-5 years or per state rule.

Tester certification: ASSE 5110 (backflow prevention assembly testers) is a recognized personnel certification; certification requires training, exam, and recertification (commonly every 3 years).

Enforcement ladder: written notice, re-test deadline, water service suspension, and reinstatement only after a passing test is filed; due process and appeal rights belong in the ordinance.

Premises surveys: initial survey plus periodic resurvey (commonly every 5 years or on change of occupancy/use) to catch new hazards and removed assemblies.

Backflow is reverse flow of water in a piping system; it occurs by backsiphonage (negative pressure) or backpressure (downstream pressure exceeds supply pressure).

Backsiphonage magnitude is limited by atmospheric pressure: theoretical maximum vacuum is about 14.7 psi (1 bar, 33.9 ft of water) at sea level.

Pressure unit conversions: 1 psi = 2.31 ft of water = 0.703 m of water; 1 ft of water = 0.433 psi.

Static pressure at depth: P = h × 0.433 psi/ft (fresh water); elevation change of 1 ft produces about 0.433 psi difference.

Flow equation for assemblies: Q = Cv × √ΔP (US gpm, psi); a higher Cv means lower head loss at a given flow.

Head loss in an assembly rises with the square of flow; check valves and relief valves add friction, so size assemblies to keep velocity and loss acceptable.

Cross-connection is any actual or potential link between potable water and a contamination/pollution source; an air gap is the only absolute protection.

Backpressure sources: boilers, elevated tanks, pumps, thermal expansion, and interconnected systems at higher pressure.

Backsiphonage sources: water main breaks, high-demand fire flow, nearby large users, and undersized piping that drops supply pressure below atmospheric.

Air gap (AG): physical separation of at least 2× the effective opening diameter, never less than 1 inch, above the flood-level rim; highest protection.

Reduced pressure principle assembly (RP/RPZ): two independent spring-loaded check valves plus a differential relief valve; protects against both backpressure and backsiphonage at health-hazard level.

RP relief valve opens when the differential across check 1 drops to about 2 psi (varies by manufacturer); the relief discharge indicates a failed check or fouled valve.

Double check valve assembly (DCVA): two check valves, testable; protects against backpressure and backsiphonage for non-health (pollution) hazards only.

Pressure vacuum breaker (PVB): one check plus an air-inlet valve that opens on loss of supply pressure; must be installed above the highest downstream outlet and cannot be used under backpressure.

Spill-resistant vacuum breaker (SVB): check plus air inlet with a loaded air-inlet valve; resists spitting and can be installed in pits where allowed.

Atmospheric vacuum breaker (AVB): non-testable, air inlet opens at atmospheric pressure; must be above downstream outlets, no backpressure, no continuous pressure.

Hose-bibb vacuum breaker (HBVB): non-testable, small, for sill cocks; not for continuous pressure or freezing service.

Chemical dispensing/barrier-type devices and dual-check with intermediate vent are specialty assemblies for specific applications; selection follows hazard class and local code.

Test equipment: differential pressure gauge (test kit) with high/low hoses, a bypass/bleed valve, and certified calibration; gauges typically require annual calibration.

Test sequence for RP: record supply pressure, check 1 closing differential (must hold ≥ 5 psi), check 2 closing differential (≥ 1 psi), and relief valve opening differential (≥ 2 psi).

For DCVA: record supply pressure, check 1 and check 2 closing differentials; both must hold at least 1 psi (per AWWA/ASSE practice).

For PVB: record air-inlet opening (must open at 1 psi or less of vacuum) and check valve closing differential (≥ 1 psi).

Test orientation: install gauge hoses on the correct test cocks (upstream/downstream), bleed air, and allow readings to stabilize before recording.

Leakage at test cocks, hoses, or gauge indicates faulty equipment or assembly seats; do not record a pass if the reading cannot be held.

Record format: assembly make/model/size/serial, location, tester name and certification number, date, supply pressure, each reading, pass/fail, and remarks.

A failed test requires repair and re-test; the report must be filed with the water supplier within the local deadline.

Kit maintenance: inspect hoses and fittings, verify gauge zero, and keep calibration certificates on file for inspection.

RP relief valve continuously discharging: check 1 fouled/leaking, relief valve seat damaged, or supply pressure fluctuation; disassemble, clean, and replace seats/springs as needed.

RP check 1 differential low: debris on seat, worn disc, or weak spring; clean seat, replace disc/spring kit, retest.

RP check 2 differential low: same causes; also verify relief valve sensing passage is clear.

DCVA check leaks: debris or damaged elastomer; replace check disc/seat and retest both checks.

PVB air inlet leaking water: fouled air-inlet disc or check valve; clean or replace and verify opening pressure.

SVB spitting: air-inlet loading valve or check seat worn; replace parts and confirm no discharge at normal flow.

Winterization: drain assemblies and protect exposed RP relief and PVB air inlets from freezing; freeze damage cracks bodies and seats.

Repair parts must be manufacturer-approved; after any repair, a full field test is required before returning to service.

Preventive maintenance: periodic inspection for corrosion, debris screens, and test cock operation; keep repair records with the assembly history.

ASSE 5110: professional qualification standard for backflow prevention assembly testers.

ASSE 5000 series: product standards for air gaps (5000/5010), RP assemblies (5013), DCVA (5012), PVB (5011), SVB (5014), AVB (5015), and hose-bibb vacuum breakers (5001).

AWWA C511 covers RP assemblies; AWWA M14 is the recommended practice manual for backflow prevention and cross-connection control.

Uniform Plumbing Code (UPC) and International Plumbing Code (IPC) contain cross-connection and backflow provisions; state and local amendments govern.

Safe Drinking Water Act and state primacy rules require public water systems to protect distribution systems from contamination, including CCC programs.

Installation rules: RP assemblies need adequate drainage and no flooding of the relief discharge; PVB/SVB must be installed above the highest downstream outlet.

Testing frequency is set by state/local rule, commonly annual; some jurisdictions require more frequent testing for high-hazard sites.

Certified testers must carry credentials and submit reports on approved forms; falsifying a test report is grounds for decertification and legal action.