Place a white bucket underneath the faucet. Turn on the cold water for 30 seconds. Examine the water in the bucket. If it is yellow, brown, orange or red, there is rust coming out of the faucet. Rusty water that only comes out of the cold tap is probably caused by a rusted water main.
Empty the bucket and set it under the tap again, if you did not see any discoloration. Turn on the hot water and let it run for 30 seconds. Examine the water for the same discoloration. If you see any, there is rust coming out of your faucet. Rusty hot water is usually a problem with your pipes.
Remove the bucket. Turn on the water and let it run for two minutes. If the discoloration clears up and the water begins to run clear, you have rust in your pipes.
Turn on the faucets throughout the house and check for discoloration. If rusty water comes out of each faucet, there is corrosion or rust in the water main.