I've been having trouble with the hot water pressure in my master bathroom. I have two sinks, each with their own supply lines, and while the left sink has great hot and cold pressure, the right sink has excellent cold water pressure but terrible hot water pressure. I've already cleaned the aerator and tried shutting off both hot and cold supply lines under the sink. When I disconnected the hot supply line from the valve and turned on the cold, the water blasts out, so the issue doesn't seem to be between the valve and the sink. However, when I try using the hot side to push water, it flows very slowly, almost like an old school water fountain. Could the hot water shut off valve be the culprit, or is there possibly some sediment behind that valve?
3 Answers
Definitely check for debris in the shut off valve. It's a common issue, especially if the valve is older. It could easily be clogged and affecting your water flow, so inspecting that might be a good start.
Another thing to consider is that some sink faucets use cartridges in the handles. If your hot side is using that type, it could be partially blocked. So checking there might help too.
If your shut off valve is one of those old-style ones that require several turns to close, then yeah, those can definitely clog up. The opening is pretty narrow, and they can get full of gunk over time. You might want to consider replacing them with quarter-turn valves for better flow.

Just to clarify, is your shut off valve actually a quarter turn? If that's the case, then it might be okay, but still worth checking for clogs.