The answer to 'toilet rusty water' is that rusty water in a toilet is typically caused by iron or mineral buildup in the toilet's tank or pipes. This can happen over time as the metal components corrode. Symptoms include reddish-brown water in the toilet bowl and staining on the porcelain. The good news is that this is usually a relatively easy problem to fix.
Some common solutions include flushing the toilet tank, replacing the toilet's flapper valve, or using a toilet tank cleaner to remove mineral deposits. If the issue persists or the toilet is older, you may need to replace the fill valve or other internal components. For more severe rust or corrosion, you may need to call a plumber to inspect the toilet and pipes and determine if more extensive repairs are required.