A plumber is servicing a single-handle cartridge-style faucet in a bathroom, where the client reports a constant drip from the spout even when fully closed. After shutting off the water, disassembling the handle, and removing retaining clips, the plumber extracts the cartridge. What is the most probable cause of the drip and the necessary repair?

Question: A plumber is servicing a single-handle cartridge-style faucet in a bathroom, where the client reports a constant drip from the spout even when fully closed. After shutting off the water, disassembling the handle, and removing retaining clips, the plumber extracts the cartridge. What is the most probable cause of the drip and the necessary repair?

Answer options:

• The aerator is clogged and needs cleaning.
• The O-rings on the faucet body are worn and require replacement. ✅ The cartridge seals or internal components are worn and the cartridge needs replacement.
• The supply line nuts are loose and need tightening.

Correct answer: The cartridge seals or internal components are worn and the cartridge needs replacement.

Explanation: A constant drip from a single-handle cartridge faucet typically indicates worn seals or internal components within the cartridge itself, necessitating its replacement. A clogged aerator would restrict flow, worn O-rings would cause leaks from the handle base, and loose supply line nuts would cause leaks at the connection points, not from the spout.