Step 4 · Inspect and Flush Supply Lines
With the water turned off again, use an adjustable wrench to disconnect the hot and cold supply lines from the faucet's inlet shanks. Position the bucket directly under the loose ends of the supply lines. Have a helper assist or carefully reach up and slowly open one shutoff valve at a time, directing the flow from the hose into the bucket. Let it run for a few seconds. This will flush out any debris lodged in the supply line. If the flow from the hose is strong, the line is clear, and the problem is in the faucet cartridge. If the flow is weak, the issue might be the supply line itself or the shutoff valve.