Depending on the model, this could be caused by debris in the cartridge, debris in the aerator, a stuck diverter or a malfunctioning wand.
First, it is essential to identify the model of your faucet. Please view our Find Your Product section to determine your model. Also, it is recommended that the supply lines from the shut-off valves be checked to ensure the faucet is receiving full pressure from both hot and cold supply lines.
For pullout or pulldown kitchen sink faucets:
Remove the hose from the wand and inspect the screen that is in between these items. If there is debris in the screen, rinse it off with water. Then, hold the end of the hose in the sink and turn on the water. If the pressure is good from the hose, reinstall the screen and wand. This should resolve the issue. If there is still low pressure after reinstalling the wand, then the wand would need to be replaced. If there is low water pressure from the hose, the cartridge would need to be replaced and the valve body would need to be flushed and cleaned.
For non-pullout or non-pulldown kitchen sink faucets:
Remove the aerator and rinse off any debris. If this does not resolve the issue, and if the unit also has a side spray, check the pressure from the side spray. If the side spray has good pressure, then try activating the trigger on the side spray several times to see if pressure returns to the spout. If it does not, then the diverter would need replaced. If your model uses a hardware kit (Moen part number 100886) with a diverter, then it is recommended that the hardware kit be replaced in addition to the diverter. If this does not resolve the issue (or if your faucet does not have a side sprayer), the cartridge would need to be replaced and the valve body would need to be flushed and cleaned.
For bathroom sink faucets:
Remove the aerator and rinse off any debris. If this does not resolve the issue, then the cartridge (for one-handle faucets) or cartridges (for two-handle faucets) would need to be replaced and the valve body would need to be flushed and cleaned.