The answer to 'sink rusty water' is that rusty water coming from a sink is often caused by corroded or galvanized plumbing pipes. This can happen over time as the pipes deteriorate, releasing rust and mineral deposits into the water. Symptoms include reddish or brownish colored water, staining of sinks and fixtures, and a metallic taste or odor.
To address this issue, you may need to replace the corroded pipes, either partially or fully depending on the extent of the problem. This is generally a job best handled by a professional plumber, as they have the expertise and tools to properly diagnose and fix the issue. DIY solutions like flushing the pipes or using chemical treatments may provide temporary relief, but are unlikely to address the root cause.