Usually, water pipes whistling comes from two main sources – either taps in the home or the actual pipework itself. If a single tap, or low quantities of them, are whistling while working, it is likely that a worn washer is the cause, or a loose brass screw or clogged aerator. So you should replace the faulty component with a new version to address whistling water pipes.
It is also possible that whistling sounds can emerge from toilets as well, which usually indicates an issue with the ballcock valve or the vertical overflow tube, suggesting they require repair or replacement.
To find out more, browse our blog, Why are my water pipes so noisy?