Step-by-step cleaning process:

Remove the aerator:
Using an adjustable wrench, unscrew the mesh aerator from the faucet. The aerator helps regulate the water flow and acts as a filter.

Prepare the cleaning solution:
Place the aerator in a small container.
Sprinkle a few teaspoons of citric acid over the aerator.
Pour boiling water into the container and stir to dissolve the citric acid. The reaction will begin immediately, with gas bubbles forming and scale particles dissolving.
Cleaning Action:
Let the aerator soak in the solution for about 5 minutes. You can partially cover the container to retain heat and aid the cleaning process.
After 5 minutes, you will notice the scale flakes coming off the aerator. Gently assist the process with a knife if necessary.
Final Steps:
After cleaning, put the aerator back into the faucet.
Test the water flow to make sure it is even and splash-free.