The answer to 'faucet constantly running' is that the most common causes are a worn-out washer or a problem with the faucet seat and spring. This can lead to a steady drip or stream of water from the faucet even when it's turned off. The symptoms include water constantly flowing from the faucet and higher-than-normal water bills.
For minor issues like a worn washer, this is typically a DIY repair that homeowners can do themselves by shutting off the water supply, disassembling the faucet, and replacing the washer. However, if the problem is with the faucet seat and spring or other internal components, it's best to call a professional plumber to diagnose and fix the issue properly.