The answer to 'faucet rusty water' is that it is usually caused by corroded or rusting internal components of the faucet. This can happen over time as the metal parts inside the faucet wear down and release rust particles into the water flow. Symptoms include reddish-brown discoloration in the water and a metallic taste or odor.
The solution may be as simple as replacing the faucet cartridge or aerator, which are relatively inexpensive and easy DIY fixes. However, if the issue is with the main faucet body or plumbing pipes, it's best to call a professional plumber to diagnose and repair the problem properly.