Unscrew the aerator, being careful not to lose the rubber washer (it’s a good idea to cover the drain to avoid parts falling into the drain opening). Usually, you’ll see a layer of grit on the screen surface. Brush this off and then backflush the aerator with a good stream of water and then reinstall it into the spout. This should now give you a much better-aerated flow pattern.
If there isn’t much improvement try this: remove the aerator, place it into a small plastic or glass container and pour in enough vinegar to cover it completely. Swish the liquid around for about 30 seconds and then place it to one side. Periodically agitate the vinegar and then set it aside again. Leave it for several hours or overnight if possible. Then install the aerator into the spout. This treatment should have definitely cleaned any mineral deposits from the interior of the aerator and you should now have a good flow of water.
The vinegar treatment can also be used on the clothes washer if you notice diminished water flow as it fills.
In this case turn off the hot and cold faucets that the water supply hoses are attached to. Unscrew the hoses from the faucets. Set the water temperature control on the washer to warm and set the machine to fill the position. Briefly, start machine for about five seconds (this will clear the water from the hoses). Don’t leave the machine on any longer than a few seconds or you could possibly burn out the water inlet valve solenoid. Next, fill each hose with vinegar and prop them upright so they don’t drain out. Again, leave them standing for several hours. Then reattach hoses to the faucets, turn on the water and set the machine to fill and start it up. This should have cleaned the screens of the water inlet valve and the water flow should be much improved.
The vinegar cleaning procedure usually works best in hard water areas. It is also nontoxic and environmentally friendly.