CSLB C-36 Plumbing ContractorPlanning and EstimatingHard
A plumbing contractor is reviewing a proposed piping diagram for a commercial building's storm drainage system. The diagram shows roof drains connecting directly to the sanitary sewer system. According to standard plumbing codes like the UPC, what is the MOST significant concern with this design?
- AIncreased risk of sewer gas entering the building.
- BHigher material costs due to combined piping requirements.
- CReduced efficiency of the storm drainage system.
- DPotential for overloading the sanitary sewer during heavy rainfall.
Show answer & explanationAnswer & explanation
Correct answer: D. Potential for overloading the sanitary sewer during heavy rainfall.
Plumbing codes universally prohibit connecting storm drainage (from roofs, paved areas) to the sanitary sewer system. The primary reason is that sanitary sewers are designed to handle wastewater from fixtures, not the massive volumes of rainwater during storms. Connecting them can lead to hydraulic overloading, causing sanitary sewer backups, overflows, and potential environmental contamination.
Why the other options are wrong
- A. While possible, the main concern is hydraulic overload, not primarily sewer gas, especially if traps are properly installed.
- B. Combined systems can sometimes be cheaper in material (fewer pipes), but the code prohibits it due to functional and environmental risks, not cost.
- C. The storm drainage system itself would be efficient at collecting water, but its discharge point is the problem.
Separation of Storm and Sanitary Sewers
Plumbing codes require complete separation of storm drainage systems from sanitary sewer systems to prevent overloading and contamination.
- Storm sewers handle rainwater; sanitary sewers handle wastewater.
- Connecting them can cause sanitary sewer overflows (SSOs) during storms.
- SSOs lead to public health hazards and environmental pollution.
Memory trick: Rain goes to the river, waste goes to treatment. Don't mix the two, or it's a messy stew!