What To Do After a Water Main Break, Boil-Water Advisory, or Contamination Event: Backflow Device Guidance
- bill57931
- Oct 13
- 5 min read
When your city issues a boil-water advisory, repairs a water main, or reports a contamination event, your backflow preventer becomes your building’s most important safeguard. But it’s not a filter or a purifier—it won’t make contaminated water safe to drink, and it can be damaged by debris or chemicals introduced during an event.
Here’s what our backflow maintenance Orange County experts recommend so you can protect people, equipment, and compliance.
Quick Answer: The At‑A‑Glance Checklist
Follow the utility’s advisory immediately. Do not drink, cook, or process food with tap water until cleared.
Isolate and protect. Shut down nonessential water uses; isolate sensitive equipment (ice makers, beverage machines, RO systems).
Do not disassemble the backflow assembly yourself. Wait for a certified tester.
After the “all clear,” flush and sanitize. Flush lines methodically, clean strainers, and sanitize fixtures per public health guidance.
Test your backflow preventer. Have a licensed tester verify operation; rebuild or replace if needed.
Document and report. Submit test reports to the water authority and keep records for compliance.
Our backflow maintenance Orange County experts recommend completing all five steps after any system-wide event, even if your assembly appears to be functioning.
Why Events Matter for Backflow Assemblies
Water main breaks create low or negative pressure, pulling debris and dirty water into service lines. Debris can foul check valves and relief valves, causing failures or nuisance discharge.
Boil-water advisories indicate microbiological contamination. Backflow devices do not disinfect water; they only stop reverse flow.
Chemical contamination can degrade rubber components (seats, checks, diaphragms), especially with petroleum-based products and solvents, leading to leaks or failure.
Our backflow maintenance Orange County experts recommend heightened caution after any event that introduces sediment or chemicals into the distribution system.
Step-by-Step: What To Do During and After an Advisory
During the Advisory or Event
Obey all notices. Use bottled or properly boiled water for consumption tasks.
Isolate vulnerable endpoints. Turn off ice makers, soda/bev machines, humidifiers, dental water lines, food prep sinks, and any process water taps.
Protect equipment. Shut down RO systems, water softeners, dishwashers, and booster heaters that can be damaged by sediment.
Do not bypass your backflow device. Never open bypasses or propped checks.
Once the Utility Issues the “All Clear”
Start with a cold-water flush. From the point of entry, open the lowest fixtures first and work outward and upward. Run until water is clear and chlorine residual is normal.
Clean inlet strainers. Many RPZ/DC assemblies have strainers upstream; remove and clean carefully.
Flush appliance lines. Ice makers (discard several batches), beverage lines, RO systems (replace filters and sanitize), and humidifiers per manufacturer guidance.
Sanitize fixtures. Our backflow maintenance experts recommend following CDC/local health department instructions: disinfect faucet aerators, showerheads, and food-contact fixtures.
Then flush hot-water side. Ensure water heaters reach target temperature, purge sediment, and verify an adequate disinfectant residual at outlets where applicable.
Test the Backflow Assembly
Schedule certified testing. A licensed tester should verify differential pressures, relief valve opening, and check tightness on RPZ, DCVA, PVB, or SPVB assemblies.
Watch for telltales. Continuous RPZ discharge or failure to hold indicates debris lodged on checks or relief seats—often after main breaks.
Rebuild or replace as needed. Debris or wear may require replacement of rubber kits; chemical exposure may necessitate full rebuild or new assembly. Our backflow maintenance experts recommend immediate rebuild if petroleum-based contaminants were present.
Document and Report
Record device details. Model, size, serial, location, and test results.
Submit reports. Provide documentation to your water purveyor/cross-connection control program within required timelines.
Log remediation. Keep invoices, sanitizer logs, and filter replacements for health inspectors and insurers.
Event-Specific Guidance
After a Water Main Break or Repair
Expect sediment. Our backflow maintenance experts recommend cleaning strainers and performing a thorough forward flush before testing.
Open valves slowly. Prevent water hammer that can damage checks and relief valves.
If RPZ discharges continuously post-flush, schedule a rebuild; debris likely prevents proper sealing.
During/After a Boil-Water Advisory
Your backflow device won’t make water potable. Do not consume water until the advisory is lifted.
Sanitize post-advisory. Follow health department steps for ice makers, food service fixtures, and medical/dental waterlines.
Testing is still required. Thermal cycling and sediment can change performance even if no chemicals are involved.
Chemical Contamination Events
Isolate immediately. Shut off water at the service valve if advised by the utility.
Replace elastomers if exposed to hydrocarbons/solvents. Rubber elements can absorb chemicals and fail later.
Consult the manufacturer. Material compatibility charts will guide whether a rebuild or full replacement is necessary.
Special Assemblies: What to Know
Fire Line Backflow (DCDA/RPDA):
Coordinate with your fire protection contractor.
Perform a forward flow/flush at the test header to remove debris.
Verify check performance and ensure no impairment to fire protection.
Irrigation Backflow (PVB/RPZ):
Flush irrigation zones independently—sediment can clog valves and emitters.
If the event occurs near winterization, test before and after seasonal blowout to confirm integrity.
Food Service, Healthcare, and Labs:
Follow industry-specific sanitization protocols.
Replace point-of-use filters and flush instrument lines thoroughly before resuming operations.
Our backflow maintenance experts recommend prioritizing these critical facilities for accelerated testing and clearance.
What Not To Do
Don’t assume “it looks fine” means it’s safe. Internal failures aren’t visible.
Don’t disassemble without certification. You can void approvals or cause cross-connection risks.
Don’t skip documentation. Missing test reports can lead to fines or service interruptions.
Preventive Steps for the Future
Increase testing frequency after major utility projects in your area.
Install/maintain inlet strainers where allowed to catch post-repair debris.
Keep rebuild kits on hand for mission-critical sites.
Train staff on shutoff locations, flushing order, and advisory procedures.
Maintain a device inventory with serials, last test dates, and locations to speed response.
Our backflow maintenance experts recommend adopting a written Emergency Water Safety Plan that includes these steps and contact numbers.
FAQs
Do I need to replace my backflow preventer after a boil-water advisory?
Usually no. Flush, sanitize, and test. Replace components only if testing fails or the manufacturer/authority requires it.
Can I use my water during an advisory if I have an RPZ?
No. Backflow assemblies prevent reverse flow; they do not make contaminated water safe to consume.
How soon should I test after the “all clear”?
As soon as practical, ideally within a few business days. Some jurisdictions require immediate post-event testing—check your local rules.
Call Atlas Backflow Services
When the unexpected happens, you need fast, compliant, and thorough support. Atlas Backflow Services provides certified testing, cleaning, rebuilds, and documentation for RPZ, DCVA, PVB, SPVB, and fire line assemblies.
If your property was affected by a water main break, boil-water advisory, or contamination event, contact us today. Our backflow maintenance experts recommend scheduling your post-event flush and test immediately to restore confidence in your water system and maintain compliance.
Comments