Cross-Connection Survey of a Property
Purpose
A survey that lists the backflow assemblies on a property has surveyed the equipment. The job is to list the connections: every point where something that is not drinking water can reach the drinking water, whether or not anybody installed a device there. Those are two different documents, and only the second one finds the carbonator plumbed to a bare check valve or the mop sink with a hose in the bucket. This procedure produces a point-by-point inventory with a hazard class, a backflow condition and a required protection on every entry, so the correction list writes itself.
Scope
Covers a cross-connection survey of a residential, multifamily or light commercial property: single family homes, small offices, small restaurants and retail, from the service entrance through every water outlet and connected appliance.
Does not cover testing an assembly, which the backflow annual test SOP owns, or repairing one, which the repair and retest SOP owns. Does not cover industrial process water, medical gas or fire protection system design. Where your jurisdiction reserves the specification of assembly type to a certified cross-connection control specialist, this procedure produces the inventory and hands specification to that person rather than substituting for them.
Roles and responsibilities
| Role | What they own | The handoff |
|---|---|---|
| Office | The purveyor's survey form, deadline and whether the survey was mandated or requested | Puts the required form and the deadline on the ticket, because a survey written on the wrong form gets returned unread |
| Technician | The walk, every point recorded, the hazard class and backflow condition per point | Returns the point list before any correction is quoted; a quote written first misses the points nobody thought to look for |
| Lead or certified specialist | Assembly specification where certification is required, and the correction sequence | Owns the same-day call on any unprotected high hazard found during the walk |
Procedure
Fix the scope and your own authority before you walk a single room. Confirm whether the purveyor mandated this survey, obtain the form it will be filed on, and state in writing what your certification permits you to do. Acceptance: the purveyor's requirement identified, the accepted form in hand, and a written note of whether you may specify assembly types or only inventory points. Wrong looks like walking a building and writing recommendations you are not certified to sign. Stop rule: where specification needs a certification nobody on the ticket holds, the walk still happens and the specification goes to someone who holds it. Hazard: none physical, it is a phone call and a form; the exposure is a survey signed by someone not authorized to sign it, which the purveyor rejects and the shop re-runs.
Start at the service entrance and settle premise isolation before you look inside. Locate the meter, record service size and material, and note whether a premise isolation assembly exists, with type, make, model, serial and last test date. Acceptance: service size and material recorded, plus either a fully identified assembly or an explicit "none installed" on the premise isolation line. Wrong looks like starting inside at the fixtures, which produces small problems and misses whether the property is isolated from the main at all. Stop rule: an assembly with no legible nameplate is recorded as unidentified rather than guessed at, since the wrong model drives the wrong repair kit later. Hazard: meter pits and vaults are permit-required confined spaces under 29 CFR 1910.146, so the reading is taken from grade with a light and a camera and nobody enters.
Walk the potable piping and record every point it reaches, not every device you recognize. Follow the cold and hot distribution room by room and stop at each place where potable water terminates, connects to an appliance or can be submerged. Acceptance: an itemized list with a location, what the point serves, the arrangement, and a photograph for each. Wrong looks like listing only the fittings that look like backflow devices, which is how a threaded mop sink faucet stays off the report for a decade. Stop rule: a run you cannot follow, above a hard ceiling or under a slab, is recorded as an unsurveyed segment rather than assumed clean. Hazard: this walk goes through mechanical rooms, crawl spaces and ceiling access, so hot pipe and flue surfaces stay untouched, a ladder is set on a level base at the pitch its label states, and a crawl space is entered only after the atmosphere and access are checked.
Classify each point by what the substance would do to a person, not by the fixture it sits on. Name the substance the point could introduce, then class it as a health hazard where it could cause illness or death, or a non-health hazard where it would only affect taste, odour or appearance. Acceptance: every point carries a named substance and a class, with the reason in the same line. Wrong looks like classifying by fixture type or by whether the building is commercial, neither of which defines the class: a residential hose bib feeding a garden sprayer is a health hazard, and a commercial ice machine on a proper air gap is not a cross connection at all. Stop rule: a substance you cannot identify is classed as a health hazard until its safety data sheet says otherwise, never the other way round. Hazard: identifying a substance means being near it, so read the safety data sheet before opening a chemical room, and do not open, decant or sample anything to identify it.
Mark the backflow condition at each point, because it decides what protection is even allowed. For each point ask whether the non-potable side can ever be pushed above supply pressure, which is backpressure, or whether supply pressure can fall below it, which is back-siphonage, then mark backpressure, back-siphonage or both. Acceptance: a condition marked for every point, with the reason named where backpressure exists: a pump, an elevated tank, a boiler, a compressed gas connection. Wrong looks like accepting a vacuum breaker on a point with a booster pump or carbon dioxide cylinder behind it, since a vacuum breaker of either type protects only against back-siphonage and does nothing against backpressure. Stop rule: any point marked backpressure that carries a vacuum breaker is flagged immediately rather than left for the report. Hazard: tracing a booster or a gas connection means working beside energized equipment, so nothing is opened, no cover comes off, and gas cylinders are identified by label and left alone.
Assign the required protection per point and set it beside what is actually installed. For each point, name the protection the adopted plumbing code requires for that hazard class and backflow condition, then record what is installed. Acceptance: a required protection, an installed protection and a verdict on every line, with air gaps measured at not less than twice the effective opening diameter and never less than 1 inch, per the plumbing code your jurisdiction has adopted. Wrong looks like recording "backflow preventer present" without naming the type, which hides a single check sitting where the code requires a vented device. Stop rule: an unprotected health hazard is escalated the same day under step 7 rather than entered on a list and driven away from. Hazard: measuring an air gap puts you over a sink or floor drain, so the water is off at that fixture and nothing is reached across a hot line to get a tape on it.
Deliver the report, rank the mismatches, and put the deadline on the customer's copy. Issue the point list with class, condition, required and installed protection, rank the mismatches health hazard first, and state the correction deadline. Acceptance: every point on the report including the compliant ones, mismatches ranked with health hazards at the top, the deadline stated in the same sentence as the consequence of missing it, and a copy filed on the purveyor's own form. Wrong looks like a report listing only the problems, which leaves the next surveyor unable to tell a compliant point from one nobody looked at. Stop rule: an unprotected health hazard is reported to customer and purveyor the day it is found, and the connection is isolated with the customer's agreement rather than left running until the paperwork catches up. Hazard: isolating a connection takes a fixture or appliance out of service, so the customer is told what stopped working and why, in writing, before you leave.
The record this produces
One survey report per property, filed with the purveyor and kept on the customer file: service size, material and premise isolation status; every point with its location, what it serves, the substance, the hazard class, the backflow condition, the required and installed protection and the verdict; a photograph per point; any unsurveyed segment named as such; the ranked mismatch list; and the correction deadline.
The compliant points are the half people want to drop and the half that pays for itself. The next survey starts from this list rather than from scratch, which is what makes a re-survey a couple of hours instead of a day, and a point compliant last time and not now is a finding rather than a discovery. The lead reads the unsurveyed segments, because a property with three of them has not been surveyed, it has been walked.
One worked pass, including a failure
A small restaurant in a strip unit, surveyed at the purveyor's request after a program audit. The walk produces eleven points where something other than drinking water can reach the potable supply.
Eight of the eleven come back compliant: the three compartment sink and the ice machine discharge to floor sinks with measured air gaps, the pre-rinse spray valve carries its integral vacuum breaker, the dishwasher is protected by its listed built-in arrangement, and four kitchen hose connections already carry hose connection vacuum breakers. Three do not match.
| Point | Class and condition | Required | Installed |
|---|---|---|---|
| Premise isolation at the meter | Health hazard, both conditions | Assembly per the purveyor's program | None |
| Mop sink faucet, hose in bucket | Health hazard, back-siphonage | Hose connection vacuum breaker | Threaded outlet, no device |
| Carbonated beverage machine | Health hazard, backpressure | Device listed for carbonated beverage service | Single check valve |
The carbonator is where the run takes its stop rule. It is a health hazard on backpressure, because the carbon dioxide side sits above supply pressure by design, and the single check installed is neither the listed device nor rated for that duty. Carbon dioxide pushed back through a check that passes will dissolve copper out of any copper tubing between the machine and the potable supply, which is exactly the mechanism behind documented illness at food service sites, and the tubing here is copper. Step 6's stop rule sends it to step 7 the same day rather than onto a list. With the manager's agreement the machine's water supply is isolated and tagged, the manager is given a written note of what stopped working and why, and both the purveyor and the lead are notified that afternoon.
The other two mismatches go on the ranked list rather than being corrected on the spot: the mop sink is a low-cost same-week fix, and premise isolation needs the certified specification the step 1 note said this tech could not sign. The report goes to the purveyor on its own form with all eleven points on it, the eight compliant ones included, and the correction deadline stated beside the consequence of missing it, which on this program is a shutoff notice.
References
- The plumbing code your jurisdiction has adopted, which sets the air gap dimension used in step 6 and the required protection per hazard class and backflow condition.
- Your water purveyor's cross-connection control program, which binds the customer as a condition of service and sets the survey form, the correction window and the enforcement action named in step 7.
- The certification your jurisdiction requires for a cross-connection control specialist, which governs who may specify assembly types under step 1, as distinct from the tester certification.
- See related: the Plumbing backflow annual test SOP, the backflow assembly repair and retest SOP, the hose bib vacuum breaker verification SOP, and the irrigation backflow winterization and startup SOP.