There are devices on the market advertised as "salt-free" water conditioning systems. These products are designed to reduce mineral buildup (scale) on appliances and fixtures. They are not the same as water softeners, so they have different effects on the treated water. The Region of Waterloo and City of Guelph in Canada recently conducted a study on the performance of one type of water conditioner; you can read a summary of the findings here.
The District supports the installation of salt-free devices approved for use by the State of Wisconsin.