How can I troubleshoot cause for low water pressure in certain faucets?

Question

Background:

• House has 1 pressure regulator from from street, this was just replaced.
• There are faucets/showers with satisfactory (high) pressure for cold and hot.

What I would like to troubleshoot:

• One sink has satisfactory pressure for hot water, but poor water pressure for cold water.
  • This is the kitchen sink. The shutoff valve for hot water diverts to the dish washer. The shutoff valve for the hot water and cold water have look different.
• One sink has poor water pressure for cold and hot water.
  • This is a bathroom sink. It has poor water pressure when either cold or hot water handle is fully open. It also has the same poor water pressure when both the cold and hot water handles are fully open.

I am wondering what steps can I follow to troubleshoot what is causing certain faucets to have poor pressure in these cases?

My naïve understanding of plumbing is that for both the hot and cold water "loops" the pressure should be the same throughout the house. What could be causing this poor performance in certain faucets?

Edit: per advice from crip659 I identified that for the bathroom sink the issue was indeed caused by the aerator. I am still determining how to carry out troubleshooting of the kitchen sink.

Answer 1

You are right that in a plumbing system the pressure should be equal.

The only difference from main pressure is when two or more faucets are open.

This leaves problems inside of the pipes/blockages/clogs.

I would undo the aerators on the faucets first. Sediment from hard water and water heaters tends to block them first and is the easiest to clean(vinegar).

After the problem will be at shut off valves or elbows in the system that are partial blocked.