A client complains that their single-handle kitchen faucet is difficult to move, especially when changing water temperature. The water flow is adequate, and there are no visible leaks. What is the most probable cause of this issue?

Question: A client complains that their single-handle kitchen faucet is difficult to move, especially when changing water temperature. The water flow is adequate, and there are no visible leaks. What is the most probable cause of this issue?

Answer options:

• A clogged aerator
• A worn-out O-ring on the spout ✅ Calcium buildup within the cartridge or ball assembly
• Insufficient water pressure

Correct answer: Calcium buildup within the cartridge or ball assembly

Explanation: Stiffness or difficulty in moving a single-handle faucet often indicates calcium or mineral buildup within the internal mechanisms, particularly the cartridge or ball assembly, which are responsible for mixing and controlling water flow. A clogged aerator would affect flow but not handle movement. Worn O-rings on the spout would cause leaks around the spout base. Insufficient water pressure would affect flow, not handle stiffness.