The answer to 'supply line low water pressure' is that there are several common causes, including a partially clogged or restricted water supply line, a problem with the main water shut-off valve, or an issue with the home's water pressure regulator. Symptoms may include low water flow, slow filling of sinks and tubs, and reduced water pressure throughout the home.
In many cases, the solution can be a simple DIY fix, such as cleaning out a clogged supply line or adjusting the pressure regulator. However, if the issue is with the main water shut-off valve or a more complex problem, it's best to call a professional plumber to diagnose and repair the issue.