Plumbing Plumbing Codes & Safety 2 — Questions and Answers
Question 1: What type of test is performed on a new DWV system to verify it is watertight?
- Air pressure test at 100 psi
- Water test or air test at specified pressures per code (Correct answer)
- Dye test only
- Visual inspection only
Correct answer: Water test or air test at specified pressures per code
New DWV systems are tested with either a water test (filled to the highest point) or an air test at pressures specified by the applicable plumbing code to verify no leaks.
Question 2: What is the purpose of a lead-free requirement in US plumbing codes?
- To reduce pipe weight
- To protect potable water from lead contamination in fittings and solder (Correct answer)
- To meet recycling standards
- To reduce installation costs
Correct answer: To protect potable water from lead contamination in fittings and solder
Since 2014, the Safe Drinking Water Act requires all plumbing fittings, fixtures, and solder in contact with potable water to be lead-free (less than 0.25% weighted average lead content).
Question 3: What is the minimum burial depth for a residential water service line in a climate with a 36-inch frost depth?
- 12 inches below grade
- 24 inches below grade
- At or below the local frost line (36 inches) (Correct answer)
- 48 inches below grade always
Correct answer: At or below the local frost line (36 inches)
Water service lines must be buried at or below the local frost line depth to prevent freezing; if the frost depth is 36 inches, the pipe must be buried at least 36 inches deep.
Question 4: What is 'potable water' and why is it important in plumbing codes?
- Heated water above 120°F
- Water that is safe for human consumption and meets EPA standards (Correct answer)
- Water treated with chlorine only
- Recycled greywater
Correct answer: Water that is safe for human consumption and meets EPA standards
Potable water is water that is safe for human consumption, cooking, and personal hygiene, and plumbing codes contain extensive provisions to protect it from contamination.
Question 5: What safety device is required on a gas water heater flue to prevent backdrafting?
- A pressure relief valve
- A barometric damper or draft hood (Correct answer)
- An expansion tank
- A sediment trap
Correct answer: A barometric damper or draft hood
A draft hood (barometric damper) is required on atmospherically vented gas water heaters to prevent flue gases from backdrafting into the living space.
Question 6: What is required when a new water heater is installed to protect the building from thermal expansion?
- A pressure reducing valve only
- An expansion tank on the cold water supply side (Correct answer)
- A larger T&P valve
- Additional pipe insulation
Correct answer: An expansion tank on the cold water supply side
When a check valve or backflow preventer creates a 'closed system,' an expansion tank must be installed on the cold water supply to water heater to accommodate thermal expansion.
Plumbing Plumbing Codes & Safety 2
What type of test is performed on a new DWV system to verify it is watertight?