Usually it's debri that gets washed up into a faucet or toilet fill valve. If only the water to your kitchen was turned off then it will be in your new faucet. If the whole house water was turned off then it could be in several locations. Try to separate hot from cold and different fixtures to help identify source. Often it is at the toilet fill valve.

loose washer in one tap. either shup off one or the tap. sometimes this will get to a rattle.