The answer to 'why is my water softener rusty water' is that a rusty water softener is often caused by the breakdown of internal components within the softener. This can happen over time as the softener ages and the metal parts start to corrode. Some common symptoms include reddish-brown water, staining on fixtures, and reduced water pressure.
There are a few potential solutions, depending on the severity of the issue. For minor rust buildup, you may be able to clean the softener yourself using a descaling solution or vinegar. However, if the rust is more extensive or the softener is older, you may need to replace the internal resin tank or even the entire unit. In these cases, it's best to call a professional plumber who can properly diagnose and fix the problem.