CSLB C-36 Plumbing ContractorPlanning and EstimatingEasy
A plumbing contractor is reviewing a commercial renovation blueprint that specifies the installation of a backflow prevention assembly on the main water service line. According to plumbing codes, what is the primary purpose of this device?
- ATo reduce water pressure entering the building to safe levels.
- BTo measure the exact volume of water consumed by the building.
- CTo prevent contaminated water from flowing back into the public potable water supply.
- DTo filter sediment and impurities from the incoming municipal water.
Show answer & explanationAnswer & explanation
Correct answer: C. To prevent contaminated water from flowing back into the public potable water supply.
Backflow prevention assemblies are critical safety devices designed to protect the public potable water supply from contamination. They prevent the reversal of flow (backflow) of non-potable water, which could be contaminated with chemicals, pathogens, or other pollutants, into the clean drinking water system.
Why the other options are wrong
- A. Pressure reducing valves (PRVs) reduce pressure, not backflow preventers.
- B. Water meters measure consumption, not backflow preventers.
- D. Water filters remove sediment, not backflow preventers.
Backflow Prevention
Backflow prevention devices protect public potable water by preventing the reverse flow of non-potable or contaminated water.
- Required at cross-connections where contamination risk exists.
- Different types (e.g., RPZ, DCVA) for varying hazard levels.
- Must be tested annually by certified technicians.
Memory trick: Backflow preventers block the dirty water from 'backing up' into the clean supply.