The answer to 'why is my supply line clogged' is that a supply line can become clogged due to a buildup of mineral deposits, debris, or corrosion over time. Common symptoms include low water pressure, dripping faucets, or water leaks. To fix a clogged supply line, you may be able to try unclogging it yourself, but in some cases it's best to call a professional plumber.
Mineral deposits and debris can accumulate in the supply line, especially in areas with hard water. Over time, this can restrict the flow of water and lead to a clogged line. Corrosion of the supply line material, such as copper or plastic, can also cause blockages. If the clog is severe, it may require replacing the entire supply line.