✓ TradeExamPro

TradeExamPro › Plumbing & Gas › Plumbing fundamentals

Water supply practice questions

30 questions from the plumbing fundamentals practice test.

Beta. These questions are new and are being checked by licensed tradespeople. If one looks wrong, use “Report this question” and we will fix it.

Water supply practice test

10 questions, graded as you go, with the reason for every answer. No sign-up.

What this covers

Sample questions

A clothes washer's solenoid valves cause loud banging in the supply piping. Which correction is the recognized one?

  1. Install water hammer arresters near the valves
  2. Install a larger water meter and service line
  3. Install a backflow preventer at the washer box
  4. Install a vacuum relief valve on each supply
Show the answer

A. Install water hammer arresters near the valves

A water hammer arrester has a sealed air or gas cushion that absorbs the pressure wave, and it works best close to the quick-closing valve. Backflow preventers and vacuum relief valves deal with reverse flow and negative pressure, not shock.

Reference: IPC 2021, Section 604 (water hammer); UPC 2021, Section 609; ASSE 1010

Under both the IPC and the UPC, a pressure-reducing valve is required when the static pressure of the water supply exceeds what value?

  1. 40 psi
  2. 60 psi
  3. 150 psi
  4. 80 psi
Show the answer

D. 80 psi

Both model codes limit static pressure in the building to 80 psi and call for an approved pressure-reducing valve above that. 150 psi is the setting of a typical water heater relief valve, not the limit for distribution pressure.

Reference: IPC 2021, Section 604 (excessive pressure); UPC 2021, Section 608

A pressure-reducing valve without a bypass is installed on the water service of a house. What additional problem does this create at the storage water heater?

  1. Cold water can no longer reach the bottom of the tank, so recovery slows
  2. Heated water cannot expand back toward the main, so pressure rises
  3. The burner can no longer get enough combustion air, so it makes soot
  4. The anode rod can no longer protect the tank, so the lining corrodes
Show the answer

B. Heated water cannot expand back toward the main, so pressure rises

A pressure-reducing valve, check valve or backflow preventer makes the house a closed system. Water expands when heated and, with nowhere to go, drives the pressure up until the relief valve opens. A device to control thermal expansion, usually an expansion tank, is needed.

Reference: IPC 2021, Section 607 (thermal expansion control); UPC 2021, Section 608

Other topics