Home Inspection State Practice Exam

What could cause pipes to rattle when water is turned on or off?

1. Thermal expansion of the pipes

2. Improper pipe supports

3. High water pressure

4. Contaminants in the water

The correct answer is: Improper pipe supports

Pipes can rattle when water is turned on or off primarily due to improper pipe supports. When pipes are not securely fastened or adequately supported, they may move or vibrate when water flows through them. This movement can create noise, as the pipes hit against walls, floors, or other nearby structures. Properly securing pipes with appropriate hangers or supports minimizes this movement and reduces the potential for rattling sounds. While the thermal expansion of pipes and high water pressure can indeed lead to noise issues in plumbing systems, these factors generally produce different types of sounds or issues. Thermal expansion might cause pipes to expand or contract, leading to popping noises instead of rattling, while high water pressure can lead to banging sounds known as water hammer, which typically occurs when a valve is suddenly closed. Contaminants in the water might affect water quality or lead to build-up over time but are less likely to cause immediate rattling noises in pipes. Proper support is therefore the most direct cause of rattling noises due to movement.