Backflow Incident at a Car Wash
A car wash connects to the municipal system through a 2-inch service with a reduced-pressure-principle (RPZ) backflow assembly. During a routine cross-connection survey, an inspector finds the RPZ's relief port discharging a steady trickle. The car wash owner says the assembly was 'tested last year' but cannot produce the report. The car wash uses a soap and wax injection system fed from a private well, and a hose bib at the wash bay has no vacuum breaker. The utility's cross-connection program requires annual testing and immediate correction of failures. The owner is a significant ratepayer and has asked the utility to 'look the other way until the busy season ends.'
1. Interpret the RPZ relief discharge and determine the required response.
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A steady trickle from an RPZ relief port indicates the assembly is failing - typically a fouled or failed first check or relief valve, meaning the assembly is not providing the required protection. Under the utility's program, the assembly must be tested and repaired or replaced promptly; it cannot be left in service in a failed condition.
Required response:
- Notify the owner in writing of the failure and the correction deadline.
- Require testing by a certified tester and repair by qualified personnel; re-test after repair.
- If the assembly cannot be repaired promptly, the utility may terminate or restrict service to protect the public water system - this is the enforcement lever, and it applies regardless of the customer's ratepayer status.
- Document the finding, notices, and correction.
'Looking the other way' is not an option; the utility has a duty to protect all customers.
2. The hose bib without a vacuum breaker is also a cross-connection. Explain the hazard and the fix.
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An unprotected hose bib is a cross-connection because a hose can be submerged in a bucket, soap tank, or wash water, and back-siphonage during a pressure drop can pull contaminants into the potable system. The car wash's soap and wax chemicals make this a high-hazard situation.
Fix: install a hose-bib vacuum breaker (or a permanent breakaway connection) on every hose bib, and prohibit submerged hose ends. The inspector should verify installation and add the fixtures to the survey record.
This is a simple, low-cost correction that should be required immediately, not deferred to the busy season.
3. The owner argues the RPZ 'was tested last year.' How should the utility handle the missing test report and the deferral request?
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- A verbal claim is not a test record. The utility should require the certified test report; if it cannot be produced, treat the assembly as untested and require testing now.
- Deferral is not appropriate for a failed assembly or an unprotected cross-connection. The utility's program requires annual testing and immediate correction of failures; the busy season is not a valid exception.
- Enforcement should be consistent and documented: written notice, deadline, and escalation to service restriction if not corrected. Applying the rule evenly protects the utility legally and protects public health.
- Offer practical help: provide a list of certified testers and coordinate timing so the repair can be done with minimal business disruption, which addresses the owner's real concern without compromising the program.