Faucet aerator: The faucet aerator, located at the tip of the faucet, can become clogged with sediment or mineral deposits, causing a knocking noise when the water flows.
Solution: Remove the aerator and clean it by soaking it in a vinegar solution for a few hours. Rinse thoroughly and reattach it to the faucet. If the aerator is damaged or worn out, replace it with a new one.
Loose faucet cartridge: If the faucet cartridge (the internal component that controls water flow) is loose, it can create a knocking sound when the water filter is in use.
Solution: Tighten the faucet cartridge by turning the retaining nut clockwise with a wrench. Be careful not to over-tighten, as this could damage the cartridge. If the cartridge is damaged or worn out, it may need to be replaced.
High water pressure: Excessive water pressure can cause the water to flow too quickly through the faucet and filter, creating a knocking sound.
Solution: Check the water pressure in your home and reduce it if it exceeds the recommended level. You may need to install a pressure-reducing valve if the water pressure is consistently too high.
Faulty water filter: A malfunctioning or incorrectly installed water filter can cause a knocking sound when water flows through it.
Solution: Check the filter for any damage or clogs. Replace it if it's damaged or has exceeded its lifespan. Ensure the filter is installed correctly according to the manufacturer's instructions.
If you've tried these troubleshooting steps and the knocking noise persists, it would be best to contact a qualified plumber for further inspection and repair.