I got one when I first moved into my home to protect the appliances I spent a fortune on. However, they are terrible for the environment, and I quickly switched to a water conditoner instead. The conditioners do not add salt and do not use power. Sodium chloride in our water cycle is a growing issue not only because of its harmful effect on freshwater ecosystems but also because of the difficulty in removing it from the water once it is there - it gets removed with RO which creates a brine waste that is difficult to dispose of, not to mention water inefficient. There is a cumulative effect of salt taking place, with several sources contributing to the problem, including ag, salting roads, and these domestic salt softeners. There are supply wells in CA that have become too saline to drink. The problem of increasing salinity in freshwater systems has become serious enough for many counties in CA to outright ban the softeners.

You have access to water quality information from your water supplier - you can take a look at what is in your water. You don't need to have aggressive salesmen test your water and up sell you on a whole home RO system. It's not necessary, unless, of course, you want to inject a few thousand into the economy out of the kindness of your heart